# RECORD 3bbf88ea5271189e3329337f57932674d7aa341e # TITLE: The Spatial Dimension of House Prices # YEAR: 2017.0 VENUE: Architecture and the Built Environment DOI: 10.59490/abe.2017.4.1747 # AUTHORS: Yun-Long Gong # PAGES: 206 CANDIDATE TABLE PAGES (1-based): [54, 55, 56, 76, 80, 81, 83, 90, 106, 108, 118, 130, 132, 134, 135, 139, 140, 148, 168, 169] # ABSTRACT: The economic reform in China, launched in the late 1970s, gradually promotes the free mobility of capital and labour between rural and urban areas, and between cities. The following housing market reform in the late 1990s thoroughly terminates the socialist allocation of housing and introduces market forces into the housing sector. Such institutional shifts have profound effects on the evolution of the Chinese interurban housing market. Yet, little is known about the spatial behaviour of house prices across cities in the post-reform era. How do the housing markets of different cities organise across space? What is the relationship between the house price dynamics of different cities? To answer these questions, this research performs economic and econometric analysis of the spatial dimension of the Chinese interurban housing market. In addition, this research also concerns the construction of a reliable house price index in the presence of spatial heterogeneity and dependence in the urban housing market of China. A reliable house price index is essential to the analysis of house price dynamic behaviour. However, owing to the data problem, this part is conducted based on the housing market of a Dutch city. This research discovers the spatial regularities of house prices across Chinese prefecture cities in an economic common area and investigates the underlying formation process. It reveals an uneven distribution of house prices across cities, with those large and/or higher-tier cities and their neighbours having significantly higher house prices. Such an uneven pattern of house prices demonstrates the agglomeration spillovers in the interurban housing market. Two forms of spillovers are empirically examined. The first is the urban hierarchy distance effect, which is related to the position of a city in a hierarchical urban system. In general, the distance penalty of higher-tier urban centres is confirmed, that is, all else being equal, the further away a city is from the higher-tier city, the lower the house price. The second form of spillovers relates to a city’s position in a city network system, in which no hierarchical structure is imposed. In such a situation, the spillovers arise from the interaction with neighbouring cities and it is found that a city that has larger neighbours tends to have higher house prices. These two forms of spillovers are somewhat correlated with each other because a higher-tier city is always associated with a larger urban size. It i ===== PAGE 1 (score 0, numeric-paren 0, table-words 0, var-words 0) ===== The Spatial Dimension of House Prices Yunlong Gong 04 2017 ===== PAGE 54 (score 57, numeric-paren 30, table-words 10, var-words 0) ===== TABLE 2.2 Estimation of central-city house price gradient Linear/Dist Linear/Time Semi-log/Dist Semi-log/Time Log-log/Dist Log-log/Time House price House price Ln(House price) Ln(House price) Ln(House price) Ln(House price) Constant 6699.1337*** (9.66) 6636.7919*** (8.25) 8.7021*** (82.59) 8.7009*** (73.12) 9.0524*** (45.59) 9.0272*** (48.71) Distance to central city -3.6720 (-1.24) – -0.0011*** (-2.84) – – – Ln(Distance to central city) – – – – -0.1198** (-2.58) – Travel time to central city – -3.5313 (-0.89) – -0.0012** (-2.27) – – Ln(Travel time to central city) – – – – – -0.1156*** (-2.62) Dummy: Jiangsu -2893.4657*** (-2.79) -3018.9746*** (-3.04) -0.4331*** (-3.08) -0.4702*** (-3.40) -0.4260*** (-2.93) -0.4428*** (-3.10) Dummy: Anhui -3670.9179*** (-2.75) -3917.2915*** (-3.04) -0.6136*** (-3.56) -0.6767*** (-4.03) -0.7090*** (-4.73) -0.7308*** (-5.04) Time effect Yes Yes Yes Yes Yes Yes F-stats 30.27 29.51 69.17 64.73 63.22 61.92 R2 0.512 0.506 0.706 0.692 0.687 0.682 Adj.R2 0.492 0.486 0.679 0.665 0.660 0.656 AIC 3832.490 3835.200 76.90 86.64 90.04 93.03 Sample size 210 210 210 210 210 210 Notes: ** and *** denote significance at the 5% and 1% level, respectively. The t values shown in parentheses are calculated based on clustered standard errors that are robust to serial correlation of the same unit and heteroskedasticity over time. 34 The Spatial Dimension of House Prices ===== PAGE 55 (score 53, numeric-paren 24, table-words 11, var-words 2) ===== The results shown in Table 2.3 reveal that both central and subcentral cities have significantly negative distance effects on house prices when using the semi-log/log-log form and log-log/semi-log functional form. Those results also show that the semi-log/log-log form is the best one in terms of adjusted R2 and AIC criteria. However, the distance penalties are no longer significant, even at 10% significance level, for the central city in the log-log/log-log model or for the subcentral city in the semi-log/semi-log model. Thus, it is certainly correct to infer that the log-log function is more appropriate than the semi-log function for subcentral cities. It should be kept in mind that the central city always has a macro-effect that influences a larger radius while the subcentral city only has a local micro-effect. In that light, it seems that the choice of functional form is sensitive to the influence sphere of the centre. The log-log function performs beɦer when the area of influence is relatively small, while the semi-log function is more appropriate if the area is larger. These findings are in line with those of Osland et al. (2007), who found that the exponential (semi-log) function performs best when the estimation is based on a large area, while the power (log-log) function performs best if the data is restricted to a small area. TABLE 2.3 Distance effects of both central and subcentral cities Semi-log/ Semi-log Semi-log/ Log-log Log-log/ Semi-log Log-log/ Log-log Ln(House price) Ln(House price) Ln(House price) Ln(House price) Constant 8.7260*** (80.38) 8.9212*** (115.18) 8.9805*** (59.59) 9.0699*** (43.06) Distance to central city -0.0008*** (-1.98) -0.0008*** (-2.03) – – Ln(Distance to central city) – – -0.0779** (-2.06) -0.0607 (-1.27) Distance to subcentral city -0.0006 (-0.93) – -0.0010* (-1.69) – Ln(Distance to subcentral city) – -0.0701*** (-4.60) – -0.0746*** (-4.66) Dummy: Jiangsu -0.4339*** (-3.06) -0.4142*** (-2.99) -0.4269*** (-2.89) -0.4196*** (-2.96) Dummy: Anhui -0.6733*** (-4.01) -0.6530*** (-3.84) -0.7598*** (-5.24) -0.7454*** (-5.18) Time effects Yes Yes Yes Yes F-Stats 61.78 72.32 60.03 65.76 Adj.R2 0.680 0.710 0.675 0.693 AIC 75.102 51.06 79.38 65.70 Sample size 210 210 210 210 Notes: *, ** and *** denote significance at the 10%, 5% and 1% level,respectively. The t values shown in parentheses are calculated based on clustered standard errors that are robust to serial correlation of the same unit and heteroskedasticity over time. Unlike the semi-log model that only includes the effect of the central city, adding the 35 Interurban house price gradient: Effect of urban hierarchy distance on house prices ===== PAGE 56 (score 71, numeric-paren 42, table-words 9, var-words 4) ===== effects of subcentral cities raises the adjusted R2 from 0.679 to 0.710. Their added effects explain 3% more variance in interurban house prices and decrease the magnitude of the distance penalties of the central city by about 27%. Since we use different functional forms for central and subcentral cities, we cannot compare the magnitudes of their distance penalties directly. TABLE 2.4 House price and wage gradient after controlling for city amenities and characteristics House price model Wage model Regional dummies Amenities + Regional dummies Amenities + Location variables Amenities + Location variables Ln(House price) Ln(House price) Ln(House price) Ln(Wage) Constant 8.4666*** (77.39) 7.6520*** (17.77) 8.0267*** (22.26) 11.0058*** (45.97) Dummy: Jiangsu -0.4895*** (-3.46) 0.0946*** (0.66) – – Dummy: Anhui -0.8410*** (-6.90) -0.1816 (-1.34) – – Coastal city – 0.3230** (2.32) 0.3523*** (3.98) 0.0227 (0.45) Winter temperature – 0.0791** (2.58) 0.0627* (1.72) -0.0086 (-0.40) Smoke and dust emissions – -0.0008 (-1.56) -0.0013*** (-2.73) 0.0004 (0.60) Doctor – 0.0010** (2.58) 0.0008*** (2.72) 0.0004* (1.79) Student/teacher ratio – -0.0050 (-0.38) -0.0022 (-0.15) -0.0354*** (-3.46) Arable land – -0.0003* (-1.83) -0.0003 (-1.33) -0.0004** (-2.38) Distance to central city– – -0.0008*** (-2.80) -0.0003* (-1.67) Ln(Distance to subcentral city) – – -0.0329* (-1.72) -0.0131 (-1.20) Time effects Yes Yes Yes Yes F-Stats 61.04 85.58 89.47 63.22 Adj.R2 0.622 0.788 0.794 0.746 Sample size 210 207 207 207 Notes: *, ** and *** denote significance at the 10%, 5% and 1% level,respectively. The t values shown in parentheses are calculated based on clustered standard errors that are robust to serial correlation of the same unit and heteroskedasticity over time. § 2.5.3 House price gradient after controlling for city amenities and characteristics ............................................................................................................................. 36 The Spatial Dimension of House Prices ===== PAGE 57 (score 10, numeric-paren 0, table-words 3, var-words 4) ===== As suggested by the theoretical model, the negative house price gradient with respect to higher-tier cities should persist after controlling for city amenities and characteristics. Before estimating this, we first investigate the compensating house price differentials for urban amenities and characteristics. As noted earlier, the average house prices in Zhejiang, Jiangsu and Anhui provinces differ significantly from each other. This observation is further supported by the estimation results of column 1 in Table 2.4, which only contains two regional dummy variables. We assume that the observed house price differentials across provinces are actually proxies for the differences in amenities. The result of testing this hypothesis is shown in column 2 of Table 2.4. After including the variables of city amenities and characteristics, the regional effects of Jiangsu and Anhui province fall dramatically and are no longer significant, which offers some support for our hypothesis. The six variables of city amenities and characteristics, together with the two regional dummy variables, account for nearly 80% of the house price variance. As a group, the amenity and characteristic variables are statistically highly significant at the 1% significance level (the joint F-statistic is 39.98 where the 1% critical value is 2.90), and each has the anticipated sign. Among these variables, winter temperature, bordering an ocean and number of doctors have significantly positive effects, while arable land per capita has a negative effect at a significance level of 10% or beɦer. The unpleasant effect of smoke and dust emissions is marginally insignificant. The third column of Table 2.4 reports the estimation results of the model with both amenity variables and two distance measures. The two distance variables in which we are most interested still have significantly negative effects: distance to the central city is significant at the 1% level, while distance to the subcentral city at the 10% level. Compared to the semi-log / log-log model that only includes two distance variables and two regional dummies, the magnitude of the central-city house price gradient in this model does not change, but the distance penalties of the subcentral city decrease by about 50%. The point estimates of city amenities and characters are quite robust as they do not differ much from the results in column 2. Perhaps the most obvious change is that the negative effect of particulate maɦer becomes highly significant. ............................................................................................................................. § 2.6 Decomposition of interurban house price gradient ............................................................................................................................. The previous section has provided estimates of the impact of urban hierarchy distances on house prices. According to the theoretical model, the decline in the interurban house price gradient could be aɦributed either to productivity disadvantages or amenity disadvantages. This section will empirically decompose the interurban house price gradient based on Equation (7) and reveal which component contributes more to the negative price effects of remoteness from higher-tier cities. 37 Interurban house price gradient: Effect of urban hierarchy distance on house prices ===== PAGE 76 (score 107, numeric-paren 71, table-words 11, var-words 5) ===== TABLE 3.2 Estimates of nonspatial model and SLX model Dependent variable = Ln(House prices) Pooled model OLS RE ML SLX_G(RE) ML (W = W0-160 G ) SLX_T(RE) ML (W = W0-150 T ) Winter temperature 0.0617*** (5.14) 0.0262*** (2.74) 0.0258*** (2.75) 0.0260*** (2.77) Ln(Smoke and dust emission) -0.1231*** (-5.24) -0.1396*** (-4.37) -0.1297*** (-4.12) -0.1325*** (-4.22) Ln(Student/Teacher ratio) -0.4662*** (-3.82) -1.3482*** (-7.24) -1.1673*** (-6.21) -1.1815*** (-6.39) Doctor 0.0358*** (6.01) 0.0253*** (2.69) 0.0268*** (2.93) 0.0243*** (2.66) Coast 0.2537*** (4.78) 0.3009** (2.54) 0.2230* (1.93) 0.2104* (1.78) Ln(Arable land) -0.0082 (-0.11) -0.0160 (-0.13) -0.0497 (-0.40) -0.0856 (-0.71) Ln(Population density) 0.1561*** (5.29) 0.1712*** (2.91) 0.1181* (1.87) 0.1006* (1.63) Ln(Land) 0.1721*** (4.93) 0.1817** (2.55) 0.1897*** (2.72) 0.1630** (2.36) W × Ln(Population density) 0.2719*** (3.04) 0.2795*** (3.17) W × Ln(Land) 0.2590** (2.00) 0.1691 (1.35) Constant 6.4704*** (8.23) 9.2550*** (6.48) 5.3201** (2.38) 6.6990*** (3.21) R-Squared 0.823 0.923 0.925 0.925 Corr-Squared 0.764 0.785 0.787 Log-likelihood 24.544 59.043 63.849 63.973 CD test 19.551*** 7.6129*** 7.955*** 8.051*** Sample size 210 210 210 210 Notes: Corr-Squared is the squared correlation between fiɦed and actual value. t-values are reported in the parentheses. W0-160 G and W0-150 T denote the spatial interaction structure between a city and its neighbouring cities within the distance band 0 – 160 km and within the travel time band 0 – 150 min, respectively. The CD test, which detects the global cross- sectional dependence of residuals, tends to standard normal distribution under the null hypothesis. ***, ** and * indicate a 1%, 5%, 10% significance level, respectively. 56 The Spatial Dimension of House Prices ===== PAGE 77 (score 9, numeric-paren 1, table-words 0, var-words 8) ===== capita which implies no significant influence of land supply constraint. After controlling for random city-specific effects, the results in the second column do not show any noticeable changes compared to the results of pooled model. In general, a warmer winter, less industrial smoke and dust emission, a beɦer education and healthcare condition, and bordering to an ocean increases the house price of a city. Note that the estimated effect of education quality in the random effect model is much higher than that in the pooled model, while the influence of winter temperature is weakened drastically. As expected, the two variables measuring urban size have statistically and economically significant effects on house prices in both models. Interestingly, an increase in urban density has almost the same effect as an expansion in urban scale. A 1 percent increase of urban population of a city will drive up house prices by around 0.17%. The fixed effects estimation, including only the time-variant variables, also confirms the importance of climate, education quality and urban population density in determining the house prices. Overall, the explanatory variables we have chosen perform satisfactorily as indicated by a relatively high Corr-Squared statistic (0.764) which represents the squared correlation between actual and fiɦed value. However, the CD test (Pesaran 2004) detects significant global cross-section dependence in residuals, suggesting the existence of cross-city spillovers7. § 3.6.2 Results of spatial models ............................................................................................................................. Estimation of SLX model The spatial weights matrix W is vital to measuring the city network spillovers as W carries the underlying spatial interaction structure. In this paper, we expect that the network externalities are only noticeable within a certain radius; at some farther distance between the two cities, network spillovers vanish. Such spatial interaction structure can be captured by different weight matrixes. Based on geographical distance, we first divide the cities surrounding city i into three distance bands, namely 0 – 160 km, 160 – 320 km and 320 – 480 km. A spatial weight matrix for each distance band is then constructed. For instance, for a city j within distance band 0 – 160 km, the spatial weight wij of W0-160 G is defined as wij,i̸=j = d−2 ij , for 0 ≤dij < 160. (7) Geographical distance has some intrinsic pitfalls; it does not take into account the physical obstacles, such as mountains and bays. So we have also constructed spatial 7 The CD test is constructed based on the average of pair-wise correlations of the residuals of each cross-sectional unit. As N →∞, this test tends standard normal distribution under the null hypothesis of no cross-sectional correlation. 57 Network externalities in Chinese housing markets: A spatial econometric approach ===== PAGE 80 (score 21, numeric-paren 6, table-words 5, var-words 5) ===== error correlation in the SLX_G model based on different spatial weight matrixes. Assuming the remaining dependence structure is still confined to the neighbours in physical distance space, the SDM model is a beɦer choice and the results will be discussed laɦer. On the other hand, if a city is assumed to interact with the cities that are nearby on the economic-geographical space, the LM tests are in favor of the SDEM specification. TABLE 3.4 LM tests on residuals of SLX model Residuals of SLX_G model estimated in Table 3.2 LM spatial lag Robust LM spatial lag LM spatial error Robust LM spatial error W0-160 G 57.784* 59.056* 18.162* 9.434* W0-1.5 EG 0.091 1.760 17.504* 19.173* Notes: For the definition of matrix W0-160 G , see notes of Table 3.2. W0-1.5 EG has the similar definition but are constructed based on economic-geographic distance. The LM and robust LM tests, developed by Anselin et al. (2008) and Elhorst (2010b) for the spatial panel data, are based on the residuals of SLX_G model estimated in Table 3.2 and follow the χ2(1) distribution under null hypothesis. * denotes the 1% significance level. The SDEM model is estimated by a ML procedure suggested by Elhorst (2014); the results are reported in second column of Table 3.510. For the sake of comparison, the first column replicates the estimates of SLX_G model. Based on the economic-geographical distance matrix, we find a highly significant spatial autoregressive process in residuals of the SLX_G model. After controlling for the spatial error correlation, the influence of population density on its own house prices becomes highly significant at 1% significance level. The point estimates of population density and land area as well as their spillovers effects are almost in line with the estimates of SLX_G model, showing the robustness of SLX_G model in measuring the agglomeration spillovers. In contrast, the estimates for the local-specific characteristics show a noticeable discrepancy between the two models. For example, smoke and dust emission and the ratio of students to teacher no longer significantly affect the house prices, whereas land supply constraint becomes an important house price determinant in SDEM model. This discrepancy might be due to the fact that the spatial paɦern of some local-specific variables is closely related to the spatial paɦern of the residuals of SLX_G model. Estimation of SDM and SAR model As previously discussed, if the spatial interaction of house prices after controlling for 10 The following random effects SDM and SAR model are also estimated by ML procedure. The matlab routine can be found at hɦp://www.regroningen.nl/elhorst/. 60 The Spatial Dimension of House Prices ===== PAGE 81 (score 111, numeric-paren 71, table-words 13, var-words 4) ===== TABLE 3.5 Estimates of SDEM, SDM and SAR models Dependent variable = Ln(House prices) SLX_G (RE) ML (W = W0-160 G ) SDEM_G (RE) ML (W = W0-160 G ) (M = W0-1.5 EG ) SDM_G(RE) ML (W = W0-160 G ) (M = W0-160 G ) SAR_G ML (M = W0-160 G ) Winter temperature 0.0258*** (2.75) 0.0601*** (3.14) 0.0122 (1.52) 0.0126 (1.57) Ln(Smoke and dust emission) -0.1297*** (-4.12) -0.0219 (-0.74) -0.0409 (-1.54) -0.0420 (-1.59) Ln(Student/Teacher ratio) -1.1673*** (-6.21) -0.6218*** (-3.07) -0.7090*** (-4.33) -0.7080*** (-4.29) Doctor 0.0268*** (2.93) 0.0026 (0.31) 0.0065 (0.85) 0.0069 (0.90) Coast 0.2230* (1.93) 0.1560* (1.68) 0.1793* (1.91) 0.1671* (1.77) Ln(Arable land) -0.0497 (-0.40) -0.2906** (-2.40) -0.1091 (-1.09) -0.1178 (-1.24) Ln(Population density) 0.1181* (1.87) 0.1278*** (2.65) 0.2042*** (3.95) 0.1909*** (4.10) Ln(Land) 0.1897*** (2.72) 0.1702*** (2.80) 0.1737*** (3.07) 0.1757*** (3.12) W × Ln(Population density) 0.2719*** (3.04) 0.2493*** (2.91) -0.0686 (-0.85) W × Ln(Land) 0.2590** (2.00) 0.2490** (2.02) -0.0564 (-0.52) M × Error 0.7364*** (14.25) M × Ln(House prices) 0.5510*** (9.48) 0.5280*** (9.96) Constant 5.3201** (2.38) 5.5096** (2.67) 4.4485** (2.43) 3.8541*** (3.05) R-Squared 0.925 0.940 0.948 0.948 Corr-Squared 0.785 0.788 0.819 0.812 Log-likelihood 63.849 82.073 95.108 94.721 Sample size 210 210 210 210 Notes: Corr-Squared is the squared correlation between fiɦed and actual value. t-values are reported in the parentheses. For the definition of the various spatial matrixes, see notes of Table 3.2. The SDEM, SDM and SAR models are estimated by the ML procedure introduced in Elhorst (2014). ***, ** and * indicate 1%, 5%, 10% significance level, respectively. 61 Network externalities in Chinese housing markets: A spatial econometric approach ===== PAGE 82 (score 10, numeric-paren 0, table-words 3, var-words 4) ===== network spillovers occurs based on geographical proximity, the SDM model is a beɦer specification. The third column of Table 3.5 shows the ML estimates of SDM model. Again, the point estimate of spatial lag of house prices is statistically significant, suggesting the existence of remaining dependence arising from other channels. Compared to the SDEM model, which models the spatial interaction in the residuals, the magnitude of the direct effect of population density in the SDM model increases from 0.13% to 0.21%. Most importantly, the spatial lags of population density and land area have negative signs, which finding contradicts network spillovers, but these effects are not statistically significant. In this case, the SDM model collapses to the SAR model which only includes the spatial lag of house prices. The SAR model estimates presented in the fourth column of Table 3.5 are largely in line with the results of SDM model. The results of the SDM and SAR models suggest that the spatial lag of house prices also contains the information of network spillovers, which cannot be distinguished from other mechanisms that can result in spatial dependence. § 3.6.3 Network spillovers ............................................................................................................................. All of the four models, SLX, SDEM, SDM and SAR, can be used to model the network spillovers in the housing markets. The first two models directly reflect our theoretical foundation and generate local network spillovers whereas the last two models generate global spillovers which are not easy to justify11. Table 3.6 summarizes the direct and spillovers effects of the four models. For the SLX and SDEM model, the direct and spillover effects are the corresponding point estimates. On the other hand, the partial derivative approach is needed to calculate the direct and spillover effects for the SDM and SAR models. The direct effect of land area is almost the same among the four spatial models, while the direct effect of population density estimated by the SDM and SAR models is much more pronounced than that in the SLX and SDEM models. In contrast, the SDM and SAR models estimate much lower network spillovers of both population density and land area than the SLX and SDEM models do. In the SDM specification, there is no significant network spillover at all. Since the spatial lag of house prices mixes various sources of spatial interaction, and because the global spillovers assumption is not consistent with our theoretical foundation, our interpretation is based on the SLX and SDEM models, and in particular on the laɦer model which considers the remaining spatial dependence in residuals. 11 Local spillovers are those spillovers occuring only between a city and its neighbouring cities connected by a spatial weight matrix. In contrast, global spillovers are those spillovers that originate from a city and transmit to all other cities. 62 The Spatial Dimension of House Prices ===== PAGE 83 (score 55, numeric-paren 34, table-words 6, var-words 5) ===== TABLE 3.6 The estimated direct effects and spillovers RE SLX SDEM SDM SAR Direct effects Ln(Population density) 0.1712*** (2.91) 0.1181* (1.87) 0.1278*** (2.65) 0.2148*** (3.90) 0.2059*** (3.84) Ln(Land) 0.1817** (2.55) 0.1897*** (2.72) 0.1702*** (2.80) 0.1832*** (2.68) 0.1914*** (3.01) Spillovers Ln(Population density) 0.2719*** (3.04) 0.2493*** (2.91) 0.0941 (0.66) 0.1989*** (3.07) Ln(Land) 0.2590** (2.00) 0.2490** (2.02) 0.0895 (0.38) 0.1850*** (2.56) Notes: For SLX and SDEM model, the direct effect and network spillovers are exactly the point estimates, whereas the partial derivative approach is used for SDM and SAR model. The inferences of direct effects and spillovers in SDM and SAR model are based on 1000 simulations using the variance-covariance matrix implied by the ML estimates (LeSage and Pace 2009; Elhorst 2010a). t-values are reported in the parentheses. ***, ** and * indicate 1%, 5%, 10% significance level, respectively. The direct effect of the SDEM model shows that the influence of land area is bigger than the effect of population density, suggesting that, in current China, city growth is likely to be characterized by an expansion of urban scale rather than an increase in intensity. The network spillover is even more noticeable. If a city becomes 1% denser and larger, the total house price increases of neighbouring cities are about 0.25%, whereas its own house price only rises by 0.13% and 0.17%, respectively. Considering that each city on average has 8 neighbours within the radius of 160 km, the network spillover on each neighbouring city is by average around 0.03%, which is much lower than the magnitude of the direct effect. § 3.6.4 Discussion ............................................................................................................................. As previously discussed, the estimation of network spillovers depends on the choice of spatial weight matrix because this matric reflects the underlying interaction structure. In this paper, the distance band used for constructing the spatial weight matrix is somewhat arbitrarily chosen. To check the robustness of our findings, we replicated our analysis based on 4 distance bands: 120, 200, 240 and 280 km. Table B1 in the appendix reports the SDEM estimation of direct effect and network spillovers based on different matrixes. Clearly, the estimation of the direct effect is very robust to the choice of spatial matrix. The estimation of network spillovers, on the other hand, shows some variation, though small. When the definition of neighbours is restricted to the radius of 120 km, the network spillovers decrease substantially with the spillover of land area becoming insignificant. As we include more cities as neighbours, the 63 Network externalities in Chinese housing markets: A spatial econometric approach ===== PAGE 84 (score 3, numeric-paren 0, table-words 0, var-words 3) ===== magnitude of network spillover becomes a bit larger (see the results of distance band 240 and 280 km), which is in line with our expectation. Nevertheless, given that the spatial weight matrix is based on a squared inverse distance function, the majority of the network spillovers still falls into the nearby neighbours despite the total number of neighbours being increased. In this sense, we believe that the evidence on network spillovers presented in this paper is reliable. The existence of network spillovers means that, all else being equal, house price in a city surrounded by large cities are much higher than those in a city that has small neighbours. If we see high house prices as a sign of the ‘triumph of the city’, our findings would indicate a core-periphery structure in our study area. We checked this implication using Moran’s I plot, which is based on a spatial weight matrix which assumes that every city within the 160 km radius of a specific city has the same influence on that city (a bit different from the matrix defined by equation (7))12. The global Moran’s I plot (Figure C1 in the Appendix) clearly shows a positive correlation between a city’s house price and the neighbouring cities’ urban population13. In particular, almost all of the cities that are surrounded by small cities have relatively lower house prices. The local Moran’s I map, also known as local indicators of spatial association (LISA) (Anselin 1995), depicts a detailed clustering paɦern. In general, we find a ‘successful’ group (high prices – high population) in the east of the study area and a ‘lost’ group (low price – low population) in the western part. There is one exception: a coastal city (Nantong) in the east with large neighbours is characterized by relatively low prices. Yet, the paɦern that a city surrounded by small cities has high house prices is not supported. A lesson learned is that the vast number of ‘lost’ cities in the western part will not flourish in the near future, since they are unable to benefit from network spillovers of big cities. ............................................................................................................................. § 3.7 Concluding remarks ............................................................................................................................. Most studies aɦributed the spatial variation of interurban house prices to local-specific characteristics. However, the spatial clustering paɦern of house prices cannot be fully explained by these local-specific variables, pointing to the importance of spillovers. To account for spatial interaction, spatial econometrics is becoming the standard toolbox in the analysis of house prices. In particular, the spatial model with spatial lag of house prices has been widely used by researchers. Nevertheless, SAR-type models have been heavily criticized because the endogenous interaction is difficult to justify. 12 Both the global Moran’s I plot and the LISA map are calculated by the software ‘Geoda’ which is available at hɦps://geodacenter.asu.edu. 13 The Moran’s I statistic is 0.193. Based on the distribution of 999 simulations of spatially random distributed data, it is significant at 5% significance level. 64 The Spatial Dimension of House Prices ===== PAGE 90 (score 74, numeric-paren 47, table-words 9, var-words 4) ===== Appendix B.Tables ............................................................................................................................. TABLE B1 Direct effect and spillovers based on different spatial weight matrixes, SDEM W0-120 G W0-160 G W0-200 G W0-240 G W0-280 G Direct effects Ln(Population density) 0.1228*** (2.60) 0.1278*** (2.65) 0.1348*** (2.80) 0.1319*** (2.65) 0.1361*** (2.74) Ln(Land) 0.1412** (2.32) 0.1702*** (2.80) 0.1753*** (2.85) 0.1716*** (2.77) 0.1770*** (2.78) Spillovers Ln(Population density) 0.1198* (1.78) 0.2493*** (2.91) 0.2484*** (2.70) 0.2765*** (2.76) 0.2894*** (2.69) Ln(Land) 0.0589 (0.63) 0.2490** (2.02) 0.2504* (1.93) 0.2747* (1.94) 0.3127* (1.93) Notes: The direct effects and network spillovers are estimated by the spatial Durbin error model specified in equation (3), with M = W0-1.5 EG . The spatial weight matrixes are defined in the same way as those defined in Table 3.2. t-values are reported in the parentheses. ***, ** and * indicate 1%, 5%, 10% significance level, respectively. TABLE B2 Fixed effects estimation of time-variant variables Dependent variable = Ln (House prices) Winter temperature Ln (Smoke and dust emission) Ln (Student /Teacher ratio) Doctor Ln (Population density) R-squared 0.0226*** (0.0065) 0.0200 (0.0337) -1.0950*** (0.3369) 0.0088 (0.0142) 2.0576*** (0.3739) 0.730 Notes: The robust standard errors are reported in the parentheses. ***, ** and * indicate 1%, 5%, 10% significance level, respectively. 70 The Spatial Dimension of House Prices ===== PAGE 91 (score 0, numeric-paren 0, table-words 0, var-words 0) ===== Appendix C.Figures ............................................................................................................................. FIGURE C1 Global Moran’s I plot FIGURE C2 LISA cluster map 71 Network externalities in Chinese housing markets: A spatial econometric approach ===== PAGE 106 (score 21, numeric-paren 10, table-words 4, var-words 1) ===== structure reasonably well. The average distances between the housing markets within Cluster 1 and Cluster 2 are 136.53 and 184.02, respectively, much smaller than the sample average distance (221.54). The extremely low standard deviations of Cluster 1 and Cluster 2 also confirm such findings. TABLE 4.2 Cluster membership and statistics based on Euclidean distance and JKL divergence Euclidean distance JKL divergence Membership Average within distance Membership Average within distance Average monthly growth rate (%) Cluster 1 2,3,4,5,6,7,8,9,13,15, 17,18,19,20,21,22, 25,26,27,28,29,30, 31,32,33,34 9.10 (1.49) 2,3,4,5,6,7,8,9,13,15, 17,18,19,20,21,22, 25,26,27,28,29,30, 31,32,33,34 136.53 (68.24) 0.35 (0.09) Cluster 2 1,10,11,14,16,23 10.70 (1.57) 1,11,12,14,16,23 184.02 (45.72) 0.50 (0.13) Cluster 3 24 24 0.78 Cluster 4 12 10 0.41 Sample 10.79 (3.05) 221.54 (173.21) 0.39 (0.13) Notes: For the cluster membership, only the ID of the city is presented. Readers can refer to Table B1 for the names of the cities. The numbers in parentheses are the standard deviations. The average within distance is the mean of all city-pair distances within the same cluster. After obtaining the mean monthly growth rate for each city throughout the sample period, the average monthly growth rate reported in the table is the average of mean growth rate across cities in the same cluster. In a broad sense, the classification results can reduce to a two-cluster solution. One is Cluster 1, which contains mainly slow-growing markets with an average monthly growth rate of 0.35%. The other combines Clusters 2, 3 and 4, which contain markets with relatively higher appreciation rates (see Table 4.2) and are considered to be “red-hot” markets. There is a much higher degree of heterogeneity within these red-hot markets, however. Compared to the difference in house price appreciation rates, the most striking divergence between the two broad groups is that, referring back to Figure 4.2, the red-hot markets experienced tremendous house price appreciation in the second half of the period, whereas house price growth during the first half of the period makes the most important contribution for the cities in Cluster 1. One can also easily identify a spatial paɦern in the house price dynamics of cities with red-hot markets located in Eastern China, as well as others that are mainly in the remaining “peripheral” regions. 86 The Spatial Dimension of House Prices ===== PAGE 107 (score 13, numeric-paren 1, table-words 5, var-words 2) ===== FIGURE 4.5 Spatial distribution of sample cities and their membership based on JKL divergence § 4.5.3 Do structural changes maɢer? ............................................................................................................................. The classification analysis of the whole period relies on the premise that the housing market structure of a city does not change. In other words, the relationship between any two cities’ housing markets is stable throughout the sample period. This assumption may not hold given the evolving conditions of the nascent Chinese housing market. To explore whether structural changes affect previous classification results, I split the sample into subsamples and perform the classification analysis on each subsample. If there is no structural change, the classification results will be highly consistent among the subsamples, as well as with the clusters presented in Table 4.2. Otherwise, some quite different cluster demarcations will be observed. The house price appreciation trajectories depicted in Figure 4.1 indicate that house price changes among sample cities are quite volatile during the first half of the period and the recent period. Thus, I divide the sample period into three sub-periods: 2005–2010 (66 observations), 2011–2013 (36 observations) and 2014–2016 (30 observations). For each sub-period, the JKL divergence is calculated based on an AR(3) specification. The average JKL distances between cities as well as the associated standard deviations are reported in the last row of Table 4.3. The average distance between housing markets in the period 2014–2016 (196.79) is much larger than the 87 The clustering paɢern of Chinese house price dynamics ===== PAGE 108 (score 28, numeric-paren 19, table-words 2, var-words 1) ===== average distance in the first (92.14) and second periods (71.23), indicating a remarkable divergence of housing markets in the recent period. While the overall housing market difference throughout the whole sample is approximately 220, as measured by JKL divergence, it can be concluded that the highly divergent market conditions in the third period account for the most important component. The hierarchical clustering method is then applied to the three subsamples, providing more details about the structural evolution of housing markets. To obtain comparable clusters across the different periods, the dendrograms of these three periods should be cut at a common “height” (divergence threshold). To do this, I first determine the appropriate number of clusters (k) for the 2014–2016 sample, which should be 5 according to Figure A2. This demarcation requires a minimum height (h) approximately 94.87. I then cut the dendrograms of the first and second period at the same height and obtain 3 clusters for both of the periods. According to the elbow plots in Figure A2, the 3-cluster demarcation is not the optimal solution for the first two periods. But only in this way can the demarcation solutions of the three sub-periods be directly compared with each other. TABLE 4.3 Cluster membership and statistics for different sample periods 2005-2010 2011-2013 2014-2016 k = 3,h = 94.87 k = 3,h = 94.87 k = 5,h = 94.87 Membership Average within distance Membership Average within distance Membership Average within distance Average monthly growth rate (%) Cluster 1 1,2,3,4,5,6, 7,8,9,11,12, 13,14,15,16, 17,18,19,22, 23,24,25,26, 27,28,29,30, 31,32,33,34 72.16 (45.72) 2,3,4,5,6,7, 8,9,11,14, 15,16,17,18, 20,21,22,25, 26,27,28,29, 30,31,32,33, 34 41.66 (24.42) 3,4,5,6,7,8, 9,19,22,25, 26,27,28,29, 30,31,32,33, 34 29.86 (11.96) -0.12 (0.09) Cluster 2 20,21 36.37 (20.21) 12,13,19 52.86 (30.65) 2,13,15,17, 18,20,21 52.71 (26.38) 0.21 (0.12) Cluster 3 10 1,10,23,24 34.67 (11.24) 1,10,12,23 46.41 (24.12) 0.56 (0.27) Cluster 4 11,14,16 47.65 (16.20) 0.89 (0.16) Cluster 5 24 1.82 Sample 92.14 (73.90) 71.23 (66.48) 196.79 (275.54) 0.17 (0.46) Notes: The same notes as Table 4.2. In both the 2005–2010 period and the 2011–2013 period, one observes highly 88 The Spatial Dimension of House Prices ===== PAGE 109 (score 10, numeric-paren 0, table-words 5, var-words 0) ===== integrated, homogeneous cross-city housing markets. Most of the cities are classified into the same cluster, with a few exceptions, Shanghai(10) for instance. The most remarkable structural change between these two periods could be that a few developed eastern cities, such as Beijing(1), Shenzhen(24), Guangzhou(23) and Hangzhou(12), began to deviate from the main group during the 2011–2013 period. When turning to the 2014–2016 period, the interurban housing market diverges much more. House price growth in Shenzhen(24), where the average monthly growth rate is 1.82%, obviously stands out from the other cities. Aside from the red-hot markets that are already separated in the 2011–2013 period (1, 12 and 23 for example), a few more rapid-growth markets with monthly growth rates of 0.89% (Cluster 4), such as Hefei(11), Fuzhou(14) and Xiamen(16), are also isolated from the main group. Furthermore, there is another cluster (Cluster 2) that deviates from the main group but not by much; this group has a relatively low average monthly growth rate (0.21%) and mainly contains some lower-tier centres in Eastern and Central China, such as Ningbo(13), Fuzhou(15), Nanchang(16) and Wuhan(21). Note that a parsimonious three-cluster solution for the 2014–2016 housing markets, which merges Cluster 1 with Cluster 2, and fuses Cluster 3 with Cluster 4, is highly consistent with the classification results based on the whole period (Table 4.2). By grouping Cluster 1 and Cluster 2 in Table 4.3, one obtains precisely Cluster 1 in Table 4.2. Similarly, Cluster 2 in Table 4.2 is almost identical to the combination of Clusters 3 and 4 in Table 4.3. To summarize the findings, the Chinese interurban housing market in the early periods (2005–2013) can be considered a homogeneous market; only a few markets have distinctive dynamic paɦerns of house prices. In the recent period (after 2014), the interurban housing market begins to diverge; not only do the markets of the most important centres of the three main economic regions stand out remarkably, the markets of some lower-tier centres are also isolated. Given this sudden structural change, it is not surprising to see that the clustering paɦern of the 2014–2016 period almost determines the classification results based on the whole period. § 4.5.4 The effectiveness of geographical and economic divisions ............................................................................................................................. The classification results suggest that geography seems to play a role in the homogeneous clustering of the city-level housing markets. In this section, I will test the effectiveness of the traditional geographical demarcation in describing the interurban housing market structure. This classification scheme was introduced by NBSC in 2011 and divides all of China into four regions: Eastern, Central, Western and Northeast China (see Figure 4.5). In addition, I also examine whether the city-tier system of demarcation based on economic factors can produce meaningful groups of housing markets. There are presently several versions of the city-tier division system available, 89 The clustering paɢern of Chinese house price dynamics ===== PAGE 118 (score 119, numeric-paren 100, table-words 2, var-words 0) ===== Appendix C.The AR(3) estimation ............................................................................................................................. TABLE C1 The AR(3) estimation of selected cities Lag 1 Lag 2 Lag 3 Intercept R-squared BG test Tianjin 0.6423*** (0.088) -0.0355 (0.105) 0.2180** (0.093) 0.0922* (0.052) 0.504 8.30** Taiyuan 0.2663*** (0.084) -0.0502 (0.087) 0.3104*** (0.081) 0.0847 (0.055) 0.179 27.64*** Shenyang 0.4988*** (0.089) 0.0611 (0.098) 0.1395 (0.087) 0.0922 (0.057) 0.380 3.33 Changchun 0.4762*** (0.089) 0.0576 (0.097) -0.0414 (0.085) 0.1743** (0.075) 0.249 26.12*** Shanghai 1.0636*** (0.090) -0.2565* (0.130) 0.0715 (0.090) 0.0772* (0.040) 0.801 1.65 Ningbo 0.7572*** (0.089) -0.0572 (0.111) 0.0777 (0.089) 0.0768 (0.051) 0.580 3.00 Hefei 0.7352*** (0.087) 0.2850*** (0.102) -0.1992** (0.097) 0.0982 (0.065) 0.640 13.24*** Nanchang 0.5306*** (0.089) 0.0566 (0.100) 0.1114 (0.089) 0.1336** (0.061) 0.389 1.01 Zhengzhou 0.5888*** (0.089) 0.0147 (0.103) 0.1432 (0.090) 0.1086** (0.047) 0.447 4.30 Changsha 0.5207*** (0.088) 0.2283** (0.095) -0.1019 (0.082) 0.1517** (0.070) 0.418 6.32 Guangzhou 0.5805*** (0.089) 0.2104** (0.102) -0.0348 (0.091) 0.1422* (0.080) 0.512 3.81 Chengdu 0.5154*** (0.089) 0.2242** (0.096) 0.0024 (0.088) 0.0686* (0.041) 0.471 2.07 Guiyang 0.5804*** (0.089) -0.0476 (0.103) 0.0299 (0.089) 0.1588*** (0.061) 0.318 5.89 Xian 0.0792 (0.087) 0.2755*** (0.084) 0.2213** (0.086) 0.1492* (0.078) 0.179 2.79 Yinchuan 0.1882** (0.090) 0.4658*** (0.081) 0.0623 (0.090) 0.0922* (0.054) 0.369 1.38 Notes: The standard errors are reported in the parentheses. The BG test represents the Breusch-Godfrey test, following the χ2 3 distribution under the null hypothesis of no serial correlation of order up to 3. ***, ** and * indicate 1%, 5%, 10% significance level, respectively. 98 The Spatial Dimension of House Prices ===== PAGE 119 (score 2, numeric-paren 0, table-words 0, var-words 2) ===== 5 Spatial interrelations of Chinese housing markets: Spatial causality, convergence and diffusion Published as: Gong, Y., Hu, J., Boelhouwer, P., 2016. Spatial interrelations of Chinese housing markets: Spatial causality, convergence and diffusion. Regional Science and Urban Economics, 59:103-117. Abstract: This paper comprehensively tests the spatial interrelationships of 10 housing markets in the Pan-Pearl River Delta (Pan-PRD) in China, including the properties of spatial causality, convergence and diffusion paɦerns. The pairwise Toda-Yamamoto Granger causality tests suggest widely existing leading-lag relationships between housing markets; a unidirectional causal flow from the eastern-central area to western China can be tentatively confirmed. However, there is a lack of sufficient evidence supporting pairwise long-run cointegration and convergence, indicating a diverged interurban housing market in the Pan-PRD. In the short run, the spatial-temporal diffusion model manifests the importance of the spillover effect from neighbouring cities in predicting one city’s house price changes. Furthermore, the generalized impulse response functions (GIRFs) clearly depict the transmission paɦern of shocks to one chosen city. The diffusion paɦern is characterized by the fact that the shocks first spread to nearby cities with cities further away taking a longer time to respond. Keywords: Spatial causality, long-run convergence, ripple effect, diffusion, house prices, China JEL: C31, C33, R21, R31 ............................................................................................................................. § 5.1 Introduction ............................................................................................................................. After the financial crisis in 2008, many governments have been aɦempting to stimulate depressed housing markets through policy interventions. However, whether the interventions can work as expected relies heavily on our understanding of housing markets. To provide deeper insights into house price behaviour, many scholars advocate an investigation into a series of interrelated regional markets rather than a single national market (Meen 1996; Yunus and Swanson 2013). Indeed, the structure 99 Spatial interrelations of Chinese housing markets: Spatial causality, convergence and diffusion ===== PAGE 130 (score 15, numeric-paren 1, table-words 3, var-words 2) ===== are integrated of order one, i.e., I(1). The ADF tests provide preliminary evidence that house prices of different cities are integrated of different orders. The ADF test has very low power in distinguishing highly persistent stationary processes from non-stationary processes; the power is lower when a deterministic trend is included in the test. Thus, an efficient unit root test, the Dickey-Fuller generalized least square (DF-GLS) test proposed by Ellioɦ et al. (1996), is also conducted. The results in the second and fifth column of Table 5.1 are largely consistent with the ADF test, except that the level house price determination of Xiamen is a unit root process. TABLE 5.1 Unit root test level 1st difference ADF DF-GLS KPSS ADF DF-GLS KPSS Guangzhou -3.886(2)** -3.361(2)** 0.080(9) -3.467(1)** -3.494(1)** 0.056(8) Shenzhen -2.179(1) -2.209(1) 0.121(9)* -3.477(0)** -3.510(0)** 0.078(8) Fuzhou -2.538(2) -1.399(2) 0.157(9)** -3.642(1)** -3.574(1)*** 0.085(8) Xiamen -3.391(2)* -2.404(2) 0.103(9) -3.784(1)** -3.642(1)*** 0.086(8) Nanchang -1.411(1) -0.957(1) 0.199(9)** -6.037(0)*** -5.233(0)*** 0.051(8) Changsha -1.852(1) -0.962(1) 0.226(9)*** -6.596(0)*** -3.899(0)*** 0.046(8) Nanning -2.188(1) -0.862(1) 0.248(9)*** -4.579(0)*** -4.382(0)*** 0.083(8) Guiyang -1.044(1) -0.745(1) 0.286(9)*** -6.289(0)*** -5.908(0)*** 0.042(8) Kunming -1.365(1) -1.764(1) 0.148(8)** -7.070(0)*** -5.161(0)*** 0.092(7) Chengdu -2.623(2) -2.144(2) 0.127(9)* -3.628(1)** -3.347(1)** 0.055(8) Notes: All the models include an intercept and a deterministic trend. Numbers shown in parentheses are the lag length or bandwidth. For the Augmented Dickey-Fuller (ADF) test (Dickey and Fuller 1979), the lag length for level variables is selected using the Bayesian Information Criterion (BIC) with the maximum lag length being set to 12. DF-GLS unit root tests (Ellioɦ et al. 1996) use the same lag length chosen for ADF test. For KPSS test (Kwiatkowski et al. 1992), the bandwidth is selected by Newey-West method. In all the cases, the lag length for first difference variables equals to the lag length for level variables minus one. The null hypothesis for ADF and DF-GLS tests is having a unit root, but stationary for the KPSS test. *, ** and *** indicate significance at the 10%, 5% and 1% level, respectively. Table 5.1(column 3 and 6) also presents the results of the KPSS test (Kwiatkowski et al. 1992), which has the null hypothesis of stationary. The KPSS results support that Xiamen’s house price series is I(0), in accordance with the ADF test but in contradiction to the DF-GLS test. The evidence for the integration order of the Xiamen price series appears to be mildly confusing. Given that the KPSS statistic is very close to the 10% critical value (0.119), it is reasonable to assume Xiamen’s price process to be I(1) for the following analysis 10. 10 One reviewer pointed out that house prices are very likely to display an asymmetric adjustment, reducing the 110 The Spatial Dimension of House Prices ===== PAGE 131 (score 6, numeric-paren 0, table-words 2, var-words 2) ===== Because not all the house price series are integrated of the same order, the pairwise Toda-Yamamoto Granger causality procedure is preferable in this analysis. According to information criteria, such as AIC and BIC, the optimal lag lengths for most of the city-pair VARs are 2 and 3. To largely ensure that the residuals are close to white noise, we proceed using the VAR(3 + d) system in which d is the maximum integration order of the city pair. The results of Toda-Yamamoto Granger causality tests are reported in Table 5.2, where the null hypothesis is that column cities do not Granger cause row cities. Overall, in most of the city pairs, we find significant evidence of bilateral or unidirectional leading-lag relations; however, the causality paɦern is very complicated 11. Certain literature focusing on housing market interaction, such as Clapp et al. (1995) and Chen et al. (2011), has claimed that the house price interrelation (or causality) only occurs between neighbouring markets. Our results cast doubt on this conclusion because leading-lag relationships are found in many city pairs where the two cities are separated by very long distances. Conversely, there is no spatial causality in certain short-distance city pairs, such as Xiamen and Fuzhou. Similarly, Pollakowski and Ray (1997) and Luo et al. (2007) also found significant causality between non-contiguous regions. Such complicated causality paɦerns may be largely due to economic relations rather than behavioural reasons (Pollakowski and Ray 1997). To further examine the results, the cities in the system are divided into two groups: the eastern-central group including the first six cities in Table 5.2 and the western group containing the remaining cities. We tentatively find a general unidirectional causal flow from the eastern-central area to western China. The historical house price information of all eastern-central cities, except Xiamen, can significantly contribute to predicting the house prices of western cities. The opposite, conversely, can hardly be true given the largely insignificant Granger causality test results in the lower-left panel. However, among the four western cities, the housing markets of Kunming and Chengdu appear to play a role in predicting house price behaviours in eastern-central cities. The above findings are closely related to the socio-economic disparities between eastern, central and western China. Considering that eastern-central cities are generally more developed than western ones, it can be expected that their market dynamics can lead housing market behaviours in the remaining cities. Chengdu is an exception in western cities, given its status as the financial and economic centre of western China. Consequently, the mutual leading-lag relationships between Chengdu and most power of traditional unit root tests. Thus, we employed the momentum threshold autoregressive (MTAR) asymmetric unit root test proposed by Enders and Granger (1998) to test the integration order of 10 cities’ house price indexes. However, the results, which are available upon request, do not turn over the finding that all the cities are I(1) process except for Guangzhou. 11 It should be noted that, throughout the paper, when we say “a market leads or causes another market in the Granger sense”, we cannot exclude the possibility that such correlation is caused by common shocks. 111 Spatial interrelations of Chinese housing markets: Spatial causality, convergence and diffusion ===== PAGE 132 (score 169, numeric-paren 149, table-words 1, var-words 0) ===== TABLE 5.2 Toda-Yamamoto Granger causality test Guangzhou Shenzhen Fuzhou Xiamen Nanchang Changsha Nanning Guiyang Kunming Chengdu Guangzhou 25.63*** (0.000) 6.47* (0.091) 50.54*** (0.000) 11.13*** (0.011) 14.10*** (0.003) 11.25*** (0.010) 9.47** (0.024) 4.41 (0.220) 9.16** (0.027) Shenzhen 13.82 (0.003) 9.14** (0.027) 18.93*** (0.000) 6.05* (0.109) 18.76*** (0.000) 8.25** (0.041) 14.14*** (0.003) 6.22* (0.101) 8.23** (0.041) Fuzhou 2.00 (0.572) 1.52 (0.678) 7.52* (0.057) 5.04 (0.169) 7.97** (0.047) 8.52** (0.036) 6.49* (0.090) 8.26** (0.041) 6.78* (0.079) Xiamen 18.73*** (0.000) 2.32 (0.510) 3.38 (0.336) 4.10 (0.251) 2.82 (0.420) 5.28 (0.153) 2.01 (0.570) 0.28 (0.963) 0.94 (0.815) Nanchang 4.47 (0.215) 7.90** (0.048) 8.25** (0.041) 6.42* (0.093) 14.61*** (0.002) 12.22*** (0.007) 17.52*** (0.001) 11.44*** (0.010) 11.55*** (0.009) Changsha 1.03 (0.794) 5.31 (0.150) 7.48* (0.058) 6.11* (0.106) 6.74* (0.081) 13.36*** (0.004) 34.22*** (0.000) 13.29*** (0.004) 7.99** (0.046) Nanning 8.91** (0.031) 14.22*** (0.003) 4.92 (0.178) 3.52 (0.318) 5.08 (0.166) 9.51** (0.023) 19.42*** (0.000) 8.64** (0.035) 8.70** (0.034) Guiyang 0.41 (0.938) 2.37 (0.500) 2.32 (0.509) 0.67 (0.880) 5.31 (0.150) 5.07 (0.167) 5.29 (0.152) 1.38 (0.711) 7.46* (0.058) Kunming 7.27* (0.064) 11.59*** (0.009) 1.79 (0.616) 5.96 (0.113) 7.30* (0.063) 27.03*** (0.000) 8.31** (0.040) 11.68*** (0.009) 10.32** (0.016) Chengdu 5.57 (0.135) 5.24 (0.155) 16.81*** (0.001) 17.69*** (0.001) 15.25*** (0.002) 8.21** (0.042) 6.20* (0.102) 7.24* (0.064) 7.19* (0.066) Notes: Toda-Yamamoto Granger causality test is performed under VAR(3+d) system where d is the maximum integration order of house price processes in the city pair. Both intercept and deterministic time trend are included in the VAR system. The null hypotheses are that house prices in column cities do not Granger cause house prices in row cities. The asymptotic Wald statistics are reported, and the corresponding p-values are shown in parentheses. *, ** and *** indicate significance at the 10%, 5% and 1% level, respectively. 112 The Spatial Dimension of House Prices ===== PAGE 133 (score 2, numeric-paren 0, table-words 0, var-words 2) ===== eastern-central cities are no surprise. Furthermore, within either the eastern-central or western group, the significant leading-lag relationship (at least for one direction) can be found in every city pair. Given the leading position of Guangdong in the Pan-PRD, we expect that the housing markets of the two cities under its territory, namely Guangzhou and Shenzhen, will lead the markets in other cities. Indeed, Guangzhou and Shenzhen impose a significant leading influence on nearly all the other housing markets, and they are less predictable on the basis of previous information from other markets. However, these cities’ dominant role is not unique. Certain other cities appear to also have similar ‘exogenous’ properties, such as Nanchang. ............................................................................................................................. § 5.5 Long-run properties ............................................................................................................................. § 5.5.1 Cointegration and convergence test ............................................................................................................................. The previous section reveals that the 10 cities’ housing markets in the Pan-PRD are interrelated with each other. In this section, we go further to ask the question of whether these markets are tied together in the long-run, i.e., if they hold a long-run equilibrium relationship. To answer this question, the long-run cointegration and convergence properties of house prices are investigated.Two I(1) house price series p1t and p2t are said to be cointegrated if a linear combination of p1t and p2t is stationary. Since we are interested in the pairwise cointegration of house price indexes of two cities, the Engle-Granger (EG) two-step procedure (Engle and Granger 1987) is employed in this paper, which has been applied by, for example, MacDonald and Taylor (1993) to a similar question. The first step is to estimate the long-run equilibrium relationship by the following equation pit = D + βp2t + ut (3) where D is deterministic terms that may contain a constant, a deterministic trend or both. The cointegration test involved in the second step is then based on testing the unit root of residual series ut. If ut is stationary, we say that p1t and p2t are cointegrated with (1,−β). Because of the spurious regression under the null hypothesis of non-cointegration in the first stage, the residual-based ADF test in the second stage does not have the standard Dickey-Fuller distribution. Therefore, critical values for cointegration test simulated by MacKinnon (1996) are used in this paper. As noted by Holly et al.(2011) and Abboɦ and Vita (2013), conditional on cointegration, the long-run convergence of house prices necessitates two additional 113 Spatial interrelations of Chinese housing markets: Spatial causality, convergence and diffusion ===== PAGE 134 (score 38, numeric-paren 17, table-words 2, var-words 3) ===== conditions: (1) the cointegrating vector corresponding to house price series being (1,-1), and (2) the lack of a deterministic trend being presented in cointegration space. The long-run convergence property is tested by the so-called pair-wise approach, which has been used by Holmes et al. (2011) and Abboɦ and Vita (2013). Specifically, the cointegrating vector is pre-specified with form (1,-1), and then any standard unit root test can be directly used to test the stationarity of cointegrating residuals. TABLE 5.3 Engle-Granger pairwise cointegration results Shenzhen Fuzhou Xiamen Nanchang Changsha Nanning Guiyang Kunming Chengdu Shenzhen -0.633 -3.094 -2.053 -13.706 -0.837 -4.413 -0.532 -2.092 -0.520 -1.557 -0.919 -3.967 -0.723 -2.718 -0.067 -0.280 Fuzhou -0.221 -1.289 -0.855 -3.683 -2.094 -5.553 -1.716 -5.963 -1.981 -7.077 -2.204 -9.371 -2.239 -7.201 -2.711 -10.044 Xiamen -1.875 -13.728 -1.129 -4.692 -0.791 -2.390 -1.362 -5.642 -1.248 -3.800 -1.482 -5.885 -1.339 -4.200 -0.831 -3.591 Nanchang -0.501 -3.266 -2.423 -6.421 -0.604 -1.918 -3.792* -27.395** -2.136 -6.507 -3.086* -19.217* -3.172 -14.187 -2.615 -14.058 Changsha -0.025 -0.129 -1.774 -6.234 -1.279 -5.748 -3.722* -26.892** -1.657 -3.287 -3.331* -20.505* -4.069** -20.546* -2.381 -11.213 Nanning 0.309 1.225 -1.762 -6.234 -0.693 -2.155 -1.693 -5.007 -1.162 -2.189 -1.988 -6.342 -1.938 -5.058 -1.593 -4.286 Guiyang -0.580 -3.231 -2.387 -10.249 -1.498 -6.588 -3.086* -19.214* -3.435* -21.148* -2.453 -8.041 -2.907 -14.028 -2.680 -15.741 Kunming -0.511 -2.369 -2.793 -8.815 -1.438 -4.608 -3.470* -15.207 -4.479** -22.088* -2.856 -7.390 -3.118 -14.779 -3.169 -13.768 Chengdu 0.330 1.649 -2.919 -10.753 -0.661 -2.936 -2.569 -13.714 -2.420 -11.287 -2.017 -5.444 -2.601 -14.893 -2.843 -12.465 Notes: The two statistics in each cell are, respectively the τ statistic and z statistic of ADF test with the null hypothesis of no cointegration. The MacKinnon (1996) critical values are used. In each cointegration equation, the row cities are defined as dependent variables. The constant is included in the cointegration space in all city pairs except the Nanchang-Guiyang pair, in which the constant is not significant. * and ** indicate the 5% and 1% significance level, respectively. § 5.5.2 Empirical results ............................................................................................................................. Table 5.3 demonstrates the results of the pairwise Engle-Grange cointegration test. Guangzhou is excluded from cointegration analysis because it is I(0) according to our unit root test results. A brief view of the results indicates that cointegration relationships rarely exist between cities, in contrast to the widely existing leading-lag relationships. Among the city pairs that are tied together in the long-run, three cities, Nanchang, Changsha and Guiyang, form a ‘cointegration club’ within which every city cointegrates with each other. In addition, the significant long-run equilibrium relationship can also be observed in the city pair of Changsha-Kunming. We also note that none of the three eastern cities, namely Shenzhen, Fuzhou and Xiamen, is 114 The Spatial Dimension of House Prices ===== PAGE 135 (score 25, numeric-paren 11, table-words 3, var-words 1) ===== cointegrated with each other or with the remaining central and western cities. This might indicate that in the long-run, the housing market conditions in eastern cities still significantly differ from the markets of the remaining cities, although much effort has been made to promote the integration process of Pan-PRD’s economy. TABLE 5.4 Pairwise convergence results with pre-specified coefficients (1,-1) Shenzhen Fuzhou Xiamen Nanchang Changsha Nanning Guiyang Kunming Chengdu Shenzhen -0.919 -1.838 -1.071 -0.875 -0.667 -1.077 0.563 1.040 Fuzhou -0.642 -1.060 -0.796 -0.940 -1.009 -1.448 0.146 1.044 Xiamen -2.109 -0.927 -0.840 -1.047 -0.880 -1.510 0.803 1.109 Nanchang -0.853 -1.843 -0.733 -0.546 -0.612 -2.994** 0.206 0.588 Changsha -1.144 -1.607 -1.529 -2.729 -0.648 -0.465 0.348 0.614 Nanning -0.480 -2.144 -1.132 -2.090 -0.594 -0.577 0.174 0.392 Guiyang -0.882 -2.170 -1.468 -3.075* -2.900* -2.451 -0.009 -0.056 Kunming -0.480 -3.383* -1.464 -3.550** -4.012** -3.770** -2.949* -1.154 Chengdu 0.509 -4.018** -0.491 -1.810 -2.973* -3.443* -1.542 -2.124 Notes: The null hypothesis of no convergence is tested based on the residual from pit −pjt. The results of ADF test (Dickey and Fuller 1979) are reported in the lower triangle, whereas the upper triangle shows the results of DF-GLS tests (Ellioɦ et al. 1996). In the unit root test process, the constant is included, and the lag length (not reported) is automatically selected by the Bayesian Information Criterion (BIC). * and ** indicate the 5% and 1% significance level, respectively. After examining the cointegration, we proceed to test the more restricted long-run convergence properties. The pairwise cointegration results with pre-specified coefficients (1,-1) are shown in Table 5.4. The ADF test in the lower triangle suggests that among the four cointegration city pairs, there are three convergent pairs: Nanchang-Guiyang, Changsha-Guiyang and Changsha-Kunming. In addition, another seven city pairs, which are not cointegrated in the Engle-Granger cointegration test are found to be significantly converged. Considering that cointegration is a necessary condition of convergence, the convergent results of these seven pairs are a surprise. These contradictory results might be due to the low power of the ADF test in detecting the unit root. To verify the ADF test, we also perform the more efficient DF-GLS test, the results of which are reported in the upper triangle of Table 5.4. This time we find only one significantly convergent pair, the Nanchang-Guiyang pair, which is also cointegrated. Note that regardless which unit root test we used, city pairs that are convergent are rare. Therefore, it is reasonable to conclude that cointegration or convergence is unlikely to widely exist among the nine cities, which indicates a diverged interurban housing market in the Pan-PRD. To check the robustness of the cointegration and convergence test results based on the two-step procedure, we also conduct two additional tests: the pairwise Johansen cointegration test and the two-step convergence test based on the momentum threshold autoregressive (MTAR) unit root test (Enders and Granger 1998) which can allow an asymmetric adjustment. The trace statistics of the Johansen procedure, 115 Spatial interrelations of Chinese housing markets: Spatial causality, convergence and diffusion ===== PAGE 136 (score 9, numeric-paren 0, table-words 4, var-words 1) ===== computed based on a VAR(3) specification with unrestricted intercept and no trend in VAR, are reported in the lower triangle of Table A1. The null hypothesis is that the column city is not cointegrated with the row city. For those cointegrated city pairs, the upper triangle of Table A1 reports the results of the log-likelihood ratio (LR) test, which is used to test the cointegrating vector restriction (1,-1). Table A2 displays the pairwise cointegration results with pre-specified coefficients (1,-1) based on the MTAR unit root test. Both of these two powerful methods identify a similar cointegration and convergence paɦern between cities with the two-step procedure does; the results are largely in line with the lower triangle results of Table 5.4. Thus, we are confident of the previous finding that only very few city pairs are found to be cointegrated or convergent. For the following analysis, we mainly rely on the results of the two-step procedure. ............................................................................................................................. § 5.6 House price diffusion paɢern ............................................................................................................................. § 5.6.1 Spatial-temporal house price diffusion model ............................................................................................................................. Previous analysis suggests that most of the city pairs do not hold a long-run equilibrium relationship; however, a few pairs do. When modelling the house price dynamics of a city, we should consider the interrelation with both the cointegrated cities and the non-cointegrated cities. In other words, we should consider the influence from the cities that can impose a long-term effect and the cities that only have a transitory effect. In addition, the spatial dimension should also be considered because it is likely that the effect imposed by nearby cities is stronger than the influence of distant cities. The spatial-temporal house price diffusion model adopted in this paper can fully capture the characteristics along both spatial and temporal dimensions. This model is a variant of spatial-temporal diffusion model proposed by Holly et al. (2011) (the Holly model), which has been applied to investigating the effects of language border on the diffusion of house prices in Belgian markets by Helgers and Buyst (2016). However, unlike the Holly model, we do not designate a ‘dominant’ city, which is assumed to have contemporaneous effects on non-dominant cities. The reason for abandoning the ‘dominant’ city from our model specification is that the general lack of pairwise long-run cointegration relationships between cities found previously suggests that there is no city that can be seen as the long-run forcing for other cities. In our model specification, the house price series in the system excluding pit is split into two groups because of the existence of a ‘cointegration club’: one group (denoted by C) being cointegrated with pit and the other (denoted by O) not. A first order error correction specification for pit is given by ∆pit = ϕi0 ( pi,t−1 −βi¯pC i,t−1 ) +ai + ai1∆pi,t−1 + bi1∆¯pC i,t−1 + ci1∆¯pO i,t−1 + ϵit, (4) 116 The Spatial Dimension of House Prices ===== PAGE 139 (score 13, numeric-paren 6, table-words 3, var-words 0) ===== provide significant evidence of cointegration for Nanchang, Changsha and Kunming. In the case of Guiyang, we cannot reject the null hypothesis of no cointegration at the 5% significance level; however, the statistics are marginally significant at the 10% level. The third column of Table 5.5 reports the estimated long-run relationships (βi). The estimated βi are approximately distributed around the value of unity, except for Kunming. TABLE 5.5 Cointegration between the four cointegrating cities and spatial lag of their cointegrated counterparts τ statistic z statistic β Nanchang -3.561* -25.128* 0.843441 Changsha -4.541** -34.150** 1.287945 Guiyang -3.089 -18.209 0.871291 Kunming -4.069** -20.546* 0.602230 Notes: The test is based on one equation regression in which we take column cities as dependent variables and the spatial lags of their cointegrated counterparts as independent variables. The first two columns report the τ statistic and z statistic of ADF test with the null hypothesis of no cointegration. The third column reports the estimation of β. Note that the t-ratio for β is invalid in this case. * and ** indicate the 5% and 1% significance level, respectively. With βi being determined, the spatial-temporal house price dynamic model for each city can be estimated using ordinary least squares (OLS). The estimation results are summarized in Table 5.6 where the lag-orders are set to 2. These models perform reasonably well because the Breusch-Godfery test suggests no serial correlation in each regression’s residuals at least at the 5% significance level. The error correction terms, which appear in the model specification of four cities, are all significant at the 10% significance level, three of which are significant at the 5% level or above. That is, the four cities’ short-run dynamics are influenced by the deviation from the long-run equilibrium relationship. The coefficient ϕi0 indicates that the house price of Changsha responds to the disequilibrium much more rapidly than that of the other three cities. We now turn to the influence of short-term dynamics. Not surprisingly, the first-lag price changes are significantly positive in all equations. The second-order lagged price dynamics also play a role in the price equation for Fuzhou and Xiamen. Similarly, the lagged price changes from neighbouring cities (either from the cointegration group or the non-cointegration group) are also found to be statistically significant in all equations, except for Changsha and Kunming. This confirms the existence of cross-city spillover effects from the neighbouring cities, which is in accordance with the findings of Holly et al. (2011) for the UK market and Helgers and Buyst (2016) for Belgian housing markets. 119 Spatial interrelations of Chinese housing markets: Spatial causality, convergence and diffusion ===== PAGE 140 (score 112, numeric-paren 94, table-words 2, var-words 0) ===== TABLE 5.6 Estimation results of the spatial-temporal house price diffusion model City Constant Error correction Own lag effects Lag effects of cointegration group Lag effects of non- cointegrated group Adjusted R2 Serial correlation ϕi0 ai1 ai2 bi1 bi2 ci1 ci2 Guangzhou 0.0007 (0.001) – 0.4326*** (0.098) 0.0765 (0.108) – – 0.6540*** (0.182) -0.3067* (0.161) 0.514 5.452 Shenzhen 0.0011 (0.001) – 0.6464*** (0.106) -0.0038 (0.106) – – 0.9324** (0.197) - 0.7141*** (0.200) 0.527 6.035 Fuzhou 0.0005 (0.001) – 0.3074*** (0.100) 0.2321* (0.097) – – 0.5384*** (0.140) -0.2231 (0.141) 0.548 0.588 Xiamen 0.0008 (0.001) – 0.1673* (0.096) 0.1624* (0.093) – – 0.7223*** (0.167) -0.1577 (0.180) 0.477 2.344 Nanchang 0.0548* (0.028) -0.0755* (0.040) 0.3530*** (0.104) 0.0723 (0.108) 0.0737 (0.098) -0.0436 (0.096) 0.3720** (0.171) -0.0430 (0.174) 0.425 4.708 Changsha - 0.2594*** (0.062) - 0.2006*** (0.048) 0.3654*** (0.093) 0.0726 (0.092) 0.1437 (0.158) -0.0934 (0.159) 0.1763 (0.192) 0.1628 (0.195) 0.541 1.271 Nanning 0.0003 (0.001) – 0.4869*** (0.106) 0.0244 (0.101) – – 0.3624** (0.171) 0.0928 (0.170) 0.615 3.111 Guiyang 0.0414** (0.020) - 0.0696** (0.034) 0.4129*** (0.095) -0.0258 (0.092) 0.4800*** (0.109) -0.2064* (0.111) 0.0976 (0.155) -0.0413 (0.165) 0.467 7.778* Kunming 0.1915*** (0.059) - 0.1092*** (0.034) 0.3423*** (0.102) -0.0546 (0.098) 0.1323 (0.109) -0.1476 (0.106) 0.3847 (0.263) 0.0062 (0.232) 0.258 0.855 Chengdu -0.0002 (0.000) – 0.2419** (0.099) 0.0420 (0.098) – – 0.3315*** (0.120) 0.1753 (0.124) 0.550 1.934 Notes: The estimation results are based on equation (4) with lag-orders being set to 2. For the cities except Nanchang, Changsha, Guiyang and Kunming, we eliminate the error correction term and the term ‘lag effects of cointegration group’ because these cities do not have cointegrated counterparts. The “serial correlation” column reports the Breusch-Godfery serial correlation statistic test that distributes approximately as χ2 3 under the null hypothesis of no residual serial correlation. *, ** and *** indicate the 10%, 5% and 1% significance level, respectively. 120 The Spatial Dimension of House Prices ===== PAGE 141 (score 7, numeric-paren 0, table-words 3, var-words 1) ===== The regression results of spatial-temporal diffusion models presented in Table 5.6 depict a complicated dynamic system in which the historical house price changes of a city not only affect its own price changes but also influence the price changes in other cities directly or indirectly through their neighbouring cities, or through the long-run equilibrium. To intuitively illustrate the diffuse nature of house prices in a complicated system, we provide the generalized impulse response functions, which can trace the time profile of shocks both over time and space. FIGURE 5.3 Generalized impulse responses of a positive unit shock (one standard error) to Shenzhen house prices Figure 5.3 plots the generalized impulse responses of all the cities to a positive unit shock (one standard error) to the house prices of Shenzhen, one of the most developed cities in the Pan-PRD. The positive shock gradually diffuses to the remaining cities, significantly raising the house prices in the whole area (being confirmed by the bootstrap confidence interval in Figure B1 in the Appendix). However, the magnitude of the spillover effect differs across the region. Given the one standard error shock to Shenzhen, its own house prices soar approximately 3.5%, followed by Guangzhou, which rises by approximately 2%. Conversely, the increases of the other cities’ house prices are approximately 1%. This indicates a diverged interurban housing market between developed and less-developed cities. For the sake of comparison, Figure 5.4 portrays the responses to a positive stand error shock to Changsha, a city in Central China and cointegrating with the other three cities. It is clear that the unit shock to Changsha generates relatively homogenous effects on all other cities’ house prices (house prices increases are approximately between 0.8% and 1%), except for Shenzhen and Kunming. The effect on Shenzhen house prices is not significant, as indicated by the bootstrap error bounds shown in Figure B2 (refer to the Appendix). This information further supports our conclusion regarding the divergence of a few cities’ 121 Spatial interrelations of Chinese housing markets: Spatial causality, convergence and diffusion ===== PAGE 148 (score 28, numeric-paren 16, table-words 2, var-words 0) ===== ............................................................................................................................. Appendices ............................................................................................................................. Appendix A ............................................................................................................................. TABLE A1 The results of pairwise Johansen cointegration test Shenzhen Fuzhou Xiamen Nanchang Changsha Nanning Guiyang Kunming Chengdu Shenzhen Fuzhou 7.60 1.95 Xiamen 8.69 7.44 Nanchang 7.25 11.11 9.05 7.19** 0.16 1.57 Changsha 10.02 9.83 7.27 20.27** 4.45* 8.80** Nanning 10.74 12.66 9.01 12.77 10.26 2.05 Guiyang 6.81 14.52 10.30 18.03* 18.22* 13.74 0.01 Kunming 2.40 13.20 6.46 16.89* 25.04** 18.55* 17.07* Chengdu 6.75 16.61* 4.12 15.46 13.93 12.94 15.03 13.22 Notes: The lower triangle cells report the trace statistic of the pairwise Johansen cointegration test under the null hypothesis H0 : r = 0. The test is based on a VAR(3) specification, with unrestricted intercept and no trend in VAR. For the co-integrated city pairs, the upper triangle cells report the log-likelihood ratio (LR) test for the cointegrating vector restriction (1,-1). * and ** denote 5% and 1% significance level, respectively. TABLE A2 Pairwise convergence with pre-specified coefficients (1,-1) base on the MTAR unit root test Shenzhen Fuzhou Xiamen Nanchang Changsha Nanning Guiyang Kunming Chengdu Shenzhen Fuzhou 2.08(1) Xiamen 3.72(1) 0.70(2) Nanchang 1.54(1) 1.43(1) 0.48(1) Changsha 3.19(1) 3.93(2) 1.40(2) 4.87(1) Nanning 0.18(1) 2.76(1) 1.96(2) 2.15(1) 0.32(1) Guiyang 1.90(1) 2.38(1) 1.55(2) 4.73(1) 4.66(1) 3.03(1) Kunming 0.91(1) 5.17*(1) 2.17(1) 7.81**(1) 8.29**(1) 6.01*(1) 4.10(1) Chengdu 0.24(1) 4.34(1) 4.60(2) 1.67(1) 3.72(1) 5.96*(1) 1.20(1) 2.71(1) Notes: The null hypothesis of no convergence is tested based on the residual from pit −pjt. In all the models a constant is included, and the lag length is shown in the parentheses. The 5% and 1% critical values are 5.02 and 7.10, respectively. * and ** denote 5% and 1% significance level, respectively. 128 The Spatial Dimension of House Prices ===== PAGE 149 (score 3, numeric-paren 0, table-words 1, var-words 1) ===== Appendix B: Bootstrap GIRF confidence intervals ............................................................................................................................. The methods for computing the bootstrap confidence intervals of the generalized spatial-temporal impulse response functions are borrowed from Holly et al.(2011). The estimated model (7) is first used to generate B bootstrap samples. The bth bootstrap sample can be obtained by the following Data Generation Process (DGP) p(b) t = ˆa + ˆΦ1p(b) t−1 + ˆΦ2p(b) t−2 + ˆϵ(b) t , (B.1) where ˆϵ(b) t = ˆΣ 1/2v∗(b) t . The elements of v∗(b) t are recursively replaced by the values that are randomly drawn from the transformed residual matrix ˆΣ −1/2 (ˆϵ1, ˆϵ2, . . . , ˆϵt). Note that in equation (B.1), the first 2 observations are replaced by the original data. When obtaining the bootstrap sample p(b) t , we estimate the model (7) again and produce the bth bootstrap GIRF g(b) i (h) = ˆΨ (b) h ˆΣ (b)ei √ ˆσ(b) ii , for i = 1, · · · , n; h = 0, 1, · · · , H. (B.2) The lower and upper bands of 100(1 −α)% confidence interval are equivalent to the α/2 and 1 −α/2 quantiles of B g(b) i (h) for each i and h. 129 Spatial interrelations of Chinese housing markets: Spatial causality, convergence and diffusion ===== PAGE 168 (score 66, numeric-paren 54, table-words 2, var-words 3) ===== When estimating the MGWR model, we used the adaptive bi-square function to construct the weighting scheme, given that the transactions were not evenly distributed across space. In this case, the bandwidth is generally referred to as the window size, and the choice of window size is equivalent to the choice of the number of nearest neighbors. To find the optimal value, we varied the window size from 10% to 95% using a 5% interval and selected the size that yielded the lowest CV score as given by equation (18). Each annual sample has a unique optimal window size. The CV scores indicated that a 10% window size was preferred for most of the years, except for 1999, 2000 and 2002, with an optimal size of 15%, and 2003, with an optimal size of 30%. However, for the construction of price indexes, we would prefer using the same window size for all years, especially since the number of sales is almost evenly spread across the whole period. So we chose a window size of 10% for each year, leading to 60 nearest neighbors that were used in the estimation of the annual MGWR models. TABLE 6.1 Parameter estimates for structures characteristics, 2007 OLS OLSD MGWR Intercept 1480.70*** (46.93) 1405.41*** (53.71) 1395.76*** (57.51) Building period:1960-1970 -370.48*** (25.94) -389.50*** (36.67) -398.40*** (41.75) Building period:1971-1980 -311.17*** (23.36) -261.50*** (33.96) -323.50*** (41.75) Building period:1981-1990 -232.93*** (23.37) -173.08*** (32.59) -226.14*** (42.87) Building period:1991-2000 -58.64*** (21.64) -49.34* (26.55) -115.13*** (37.26) Terrace -285.65*** (35.17) -264.34*** (35.24) -187.28*** (37.32) Corner -281.36*** (31.77) -274.54*** (31.18) -192.85*** (34.07) Semidetached -122.89** (47.96) -149.50*** (47.57) -96.93** (48.73) Duplex -151.08*** (30.60) -147.24*** (30.17) -104.56*** (31.03) Notes:Standard errors are reported in parentheses; ***, ** and * denote significance at the 1% , 5% and 10% level, respectively. As an illustration, Table 6.1 shows the 2007 parameter estimates for the structures characteristics. Almost all of the estimates differ significantly from zero at the 1% level. To some extent they vary across the different models. For example, the OLS intercept term is relatively high compared to the OLSD and MGWR intercepts. Note that, since dummy variables for houses built after 2000 and for detached houses were not included, the intercept measures the price in euros of structures per square meter of living space for detached houses built after 2000. In accordance with a priori expectations, detached dwellings are more expensive than other types of houses. For 148 The Spatial Dimension of House Prices ===== PAGE 169 (score 17, numeric-paren 0, table-words 3, var-words 3) ===== all models, there is a clear tendency for the structures to become less expensive as they are geɦing older. TABLE 6.2 Summary statistics for estimated land prices OLS OLSD MGWR Mean S.D. Min Max Median Mean S.D. 1998 116.80 131.50 31.14 72.30 231.03 122.66 125.49 28.66 1999 154.64 178.50 34.85 105.95 223.66 174.07 167.77 30.39 2000 239.77 239.41 36.24 138.53 319.32 251.34 241.83 44.27 2001 214.54 235.58 47.59 110.41 295.01 229.52 226.70 48.77 2002 234.77 245.11 38.41 156.15 323.63 255.05 242.23 40.89 2003 166.07 185.11 44.23 82.12 248.23 179.93 172.26 44.55 2004 186.40 197.19 29.75 104.95 254.20 197.70 195.41 33.78 2005 226.13 224.11 36.55 127.53 299.74 214.19 205.89 35.17 2006 202.84 195.77 30.85 125.90 274.24 207.43 201.27 32.05 2007 214.87 236.73 27.96 141.46 286.91 235.07 229.25 30.99 Notes: For OLS, the land price estimates are reported. For OLSD, the columns show the weighted mean and standard deviation of the estimated land prices for 9 postcode areas where the weights are equal to the share of transactions within each postcode area. For MGWR, the columns provide summary statistics for the land price estimates of all transacted properties. Table 6.2 contains summary statistics for the estimated price per square meter of land from the three models. The three average land price series exhibit a similar paɦern over time, which differs substantially from the changes in the average transaction price of the properties (see Table A1 in the Appendix). After a sharp increase in 1999, the estimated average land price fluctuated during a couple of years, experienced a dramatic drop in 2003, and then increased again. As mentioned earlier, a virtue of MGWR is that it allows us to plot a continuous map with estimated prices of land per square meter. For the year 2007, such a map is depicted in Figure 6.1 for the city of “A”, where the land prices have been rescaled to the range [0,1]. The postcode areas are indicated as well. While the spatial paɦern in Figure 6.1 is largely consistent with the paɦern found using the OLSD model (shown in Figure A1 in the appendix), the MGWR land prices estimates do vary within some of the areas. This suggests that the use of postcode dummies, as in the OLSD model, is a rather crude strategy to incorporate spatial variation of land prices. To formally compare the performance of the three hedonic models, two statistics were calculated, the Corrected Akaike Information Criterion (AICc) and the Root Mean Square Error (RMSE). The AICc takes into account the trade-offbetween goodness of fit and degrees of freedom. The AICc expressions for the OLS and OLSD models can be found in Hurvich and Tsai (1989). And for MGWR models, it is defined by AICc = 2nln(ˆσ) + nln(2π) + n ( n + tr(S) n −2 −tr(S) ) 149 Accounting for spatial variation of land prices in hedonic imputation house price indexes: A semi-parametric approach ===== PAGE 170 (score 3, numeric-paren 0, table-words 1, var-words 1) ===== FIGURE 6.1 Price of land per square meter, 2007 where ˆσ is the estimated standard deviation of the error term and tr(S) the trace of the hat matrix described in section 6.3.2. The RMSE measures the variability of the absolute prediction errors of the models and is given by RMSE = 1 n √∑ i (pi −ˆpi)2. Table 6.3 shows the AICc and RMSE and their differences for the three models. A rule of thumb states that if the difference in the AICc for two models is larger than 3, a significant difference exists in their performance (Fotheringham et al. 2002). It can be seen that the OLSD model performs much beɦer than the OLS model in all years, as we would expect, and in turn that the MGWR model outperforms the OLSD model (except for 2003, when the difference is insignificant). The same ranking is found if the RMSE is used to assess the various models. These results confirm the earlier finding that land prices vary across space, both across and within postcode areas. Although MGWR is obviously beɦer suited to model the variation of land prices and to predict property prices, the OLSD model does a surprisingly good job. In several years, 150 The Spatial Dimension of House Prices