# RECORD c63f29dcdec077b7ee126d8f2c6b0bcc6611e6a7 # TITLE: Spatial heterogeneity in implicit housing prices: evidence from Hangzhou, China # YEAR: 2017.0 VENUE: nan DOI: 10.3846/1648715x.2016.1247021 # AUTHORS: Hai-Zhen Wen; Yilan Jin; Ling Zhang # PAGES: 14 CANDIDATE TABLE PAGES (1-based): [7, 8, 9] # ABSTRACT: Estimated coefficients in hedonic price models are generally assumed to be constant throughout the entire study area. However, increasing evidence reveals that the marginal prices of housing characteristics may vary over space and that the spatial heterogeneity problem in implicit housing prices should be given attention. Taking Hangzhou, China, as an example, this study uses the micro data of 603 residential communities in 2014 to examine spatial heterogeneity in implicit housing prices. On the basis of the traditional hedonic price model, we establish spatial expansion and geographically weighted regression (GWR) models for comparative analysis. Results show that the spatial expansion and GWR models have excellent goodness of fit and can improve the traditional hedonic price model. The mixed geographically weighted regression (MGWR) model further reveals that the implicit prices of nine housing characteristics vary significantly over space and that the impacts of the four remaining housing characteristics on housing prices are fixed throughout the entire study area. Unlike the traditional hedonic price model and spatial expansion model, the GWR/MGWR model has the unique advantage of visually providing the spatial distribution of implicit housing prices and accurately describing spatial heterogeneity. ===== PAGE 1 (score 3, numeric-paren 0, table-words 0, var-words 3) ===== Copyright © 2017 Vilnius Gediminas Technical University (VGTU) Press http://www.tandfonline.com/tspm SPATIAL HETEROGENEITY IN IMPLICIT HOUSING PRICES: EVIDENCE FROM HANGZHOU, CHINA Haizhen WEN a, Yilan JIN a, Ling ZHANG a,* a Center for Real Estate Studying, Department of Civil Engineering, Zhejiang University, 310058 Hang- zhou China Received 13 May 2015; accepted 4 April 2016 ABSTRACT. Estimated coefficients in hedonic price models are generally assumed to be constant throughout the entire study area. However, increasing evidence reveals that the marginal prices of housing characteristics may vary over space and that the spatial heterogeneity problem in implicit housing prices should be given attention. Taking Hangzhou, China, as an example, this study uses the micro data of 603 residential communities in 2014 to examine spatial heterogeneity in implicit housing prices. On the basis of the traditional hedonic price model, we establish spatial expansion and geographically weighted regression (GWR) models for comparative analysis. Results show that the spatial expansion and GWR models have excellent goodness of fit and can improve the traditional hedonic price model. The mixed geographically weighted regression (MGWR) model further reveals that the implicit prices of nine housing characteristics vary significantly over space and that the impacts of the four remaining housing characteristics on housing prices are fixed throughout the entire study area. Unlike the traditional hedonic price model and spatial expansion model, the GWR/MGWR model has the unique advantage of visually providing the spatial distribution of implicit housing prices and accurately describing spatial heterogeneity. KEYWORDS: Housing price; Spatial heterogeneity; Hedonic price model; Geographically weighted regression 1. INTRODUCTION With the acceleration of China’s urbanization pro- cess, the real estate market has developed rapidly across many cities. Along with the rapid develop- ment in Chinese housing market is the evident spatial differentiation of housing prices in some big cities, a topic that has attracted the attention of many scholars (Xu 1997; Wang, Zhu 2004; Zhou, Luo 2004; Zhou, Zhen 2008; Ma et al. 2008). Hang- zhou, well known for the West Lake, is an impor- tant central city of the Yangtze River Delta in Eastern China. The property market in Hangzhou is characterized by high supply, high demand, and sustainably rising prices, thus giving birth to the “Hangzhou phenomenon”, which is widely recog- nized by the academia and the real estate industry in China (Wen et al. 2014a). The residential mar- ket in Hangzhou has been ebullient during the last two decades, such that the average housing price once recorded 25840 RMB/m2 in 2010 as the top one in China (Hui et al. 2016). The housing mar- ket of Hangzhou is typical in China, thus, the city represents a perfect context for investigating the spatial variation of housing price, which is a key issue worthy of study. Currently, the hedonic price model is the main research method used to quantify the determi- nants of housing prices and to estimate the im- pacts of such determinants on housing prices. In the hedonic price model, the ordinary least squares (OLS) method is adopted to estimate the implicit prices of housing characteristics (Wang, Huang 2007; Hao, Chen 2007; Wen et al. 2010). However, overlooking the spatial fixity property of housing, the traditional hedonic price model assumes that housing prices are mutually independent in the spatial distribution. Such assumption may lead to bias in the model estimation results. As housing prices represent a type of spatial data, the topics of spatial dependence and heterogeneity have caught the attention of many scholars (Anselin 1988, * Corresponding author. E-mail: zlcivil@163.com International Journal of Strategic Property Management ISSN 1648-715X / eISSN 1648-9179 2017  Volume  21(1): 15–28 doi:10.3846/1648715X.2016.1247021 ===== PAGE 7 (score 44, numeric-paren 10, table-words 10, var-words 14) ===== Spatial heterogeneity in implicit housing prices: evidence from Hangzhou, China 21 In the empirical estimation of the GWR/ MGWR model, a spatial weight matrix needs to be introduced. The spatial weight function can be determined in several ways, such as through the threshold distance, inverse distance, bi-square function and Gaussian function. The results of GWR are sensitive to the choice of bandwidth. Besides assuming a predefined and fixed band- width, an adaptive bandwidth has been proven to be highly suitable in practice (McMillen, Redfearn 2010). Therefore, we chose a Gaussian function as an adaptive spatial kernel that allows the band- width to vary based on the density of house sales around each regression point, thus encapsulating a smaller area where data are rich and a larger area where data are sparse. To obtain the optimal bandwidth, Fotheringham et al. (2002) proposed that the GWR model has the best bandwidth when the value of the corrected Akaike Information Cri- terion (AICc) or the cross-validation (CV) is at the minimum. 4. RESULTS AND DISCUSSION 4.1. Traditional hedonic price model As the traditional hedonic price model, Model 1 is estimated by the OLS method. The regression results are shown in Table 2. The analysis of vari- ance results of the model show that the significant probabilities for the F value are less than 0.001, which confirms the validity of the equation and rejects the original hypothesis of all coefficients being zero. The value of the adjusted R2 is 0.567, which means that the independent variables can explain 56.7% of the variation of the dependent variable. The values of the variance inflation fac- tor of all variables are between 1.272 and 4.203, which shows that the degree of collinearity among the independent variables is not serious. Model 1 is a global model in which the implicit prices are held unchanged throughout the study area. Nine housing characteristic variables signifi- cantly affect the housing price. Except for traffic condition, the other coefficients exhibit signs that match the theoretical expectations. The implicit price of traffic condition is negative, probably be- cause private car ownership has grown rapidly during the rapid economic development period in Hangzhou and has thus reduced the dependence on public transport such as buses. The presence of buses around the residential area inevitably brings about some negative effects, such as traffic conges- tion, exhaust pollution, and noise pollution. Hence, bus lines are likely to have a negative effect on housing price. The results are substantially con- sistent with the findings of Wu et al. (2008) and Wen et al. (2014b), Wen and Tao (2015). The regression coefficient of the nearby sub- way variable does not pass the significance level of 10%, which indicates that the subway has no significant influence on housing price in the tradi- tional hedonic price model. However, from a theo- retical point of view, subways should have a signif- icant impact at least on the surrounding housing prices. As the traditional hedonic price model can estimate only the average implicit price, the re- gression coefficient of the nearby subway variable ultimately fails to reach the 10% significance level. Similarly, the building age variable in the tradi- tional hedonic price model is not significant. Fur- thermore, the statistics of Moran’s I for the spatial autocorrelation test is 0.387, and the significance level is below 0.001. These results show the obvi- ous spatial effect of housing price on the regional distribution in Hangzhou, indicating that OLS pa- rameter estimates are inefficient and t-ratios are biased (Dubin 2003). Therefore, We use the spatial extension and GWR models for further analysis. 4.2. Spatial expansion model With the interaction terms between the 13 vari- ables and the coordinates of the sample points, two spatial expansion models are estimated by OLS. Table 2. Regression results of the traditional hedonic price model Variables Coefficients t Constant 10.188*** 117.612 ln(building age) −0.011 −0.734 Inner environment 0.013 1.221 External environment 0.008 0.809 Property management 0.042*** 5.328 Sports facility 0.031*** 3.925 Nearby university 0.046*** 2.979 Living facility 0.018** 2.208 Education facility 0.033*** 3.390 Nearby subway 0.020 1.162 Traffic condition −0.002*** −3.023 ln(distance to Wulin Square) −0.067*** −3.429 ln(distance to the West Lake) −0.221*** −12.694 ln(distance to the Qianjiang New Center) −0.059*** −4.018 AICc −468.846 Adjusted R2 0.567 Note: ***,**, and * represent significance at the 1%, 5%, and 10% levels, respectively. ===== PAGE 8 (score 74, numeric-paren 47, table-words 10, var-words 7) ===== H. Wen et al. 22 The values of the variance inflation factor of all variables are less than 10, which show that the se- rious collinearity is not present in the two expan- sion models. We report only the coefficients that are at least significant at the 10% level. The results for Model 2, the one-degree spatial expansion, are shown in the second and third col- umns. The adjusted R2 is 0.671, which indicates that Model 2 can more effectively explain the vari- ations of the dependent variable and demonstrate a more favorable goodness of fit compared with Model 1. Ten ‘‘base’’ housing characteristic vari- ables have significant effects on housing prices, and five of these variables interact with location coordinates. Ten location–characteristic interac- tion terms are significant at the 10% level, which indicates that spatial heterogeneity exists in the marginal prices of these housing characteristics. For example, the regression coefficients of Living facility is 0.032 which indicate that, in general, the value of Living facility increases by 1 unit and the housing prices will increase by 3.2%. The inter- action term of U(living facility) is −0.007, which reveal that spatial heterogeneity exists in the hori- zontal direction, and for the same quality of living facility, an additional 1 km from the Wulin Square (measured horizontally) will reduce an average community housing price by 0.7%. Five variables, namely, building age, inner envi- ronment, external environment, property manage- ment, and sports facility, have significant effects on housing prices, but their interaction terms are not significant. This condition indicates that the marginal prices of these variables do not vary in the locational context. Furthermore, two variables, namely, nearby university and nearby subway, are not significant. However, their interaction terms are significant at the 10% and 5% significance lev- els, respectively, indicating that the interaction terms still have space differences to some extent. Table 3 also reports the results of Model 3, the quadratic spatial expansion model. The addition of the quadratic interaction terms in Model 3 re- sults in an improvement in the explanatory power as the adjusted R2 increases from 0.671 to 0.704. A total of 15 out of the 65 interaction variables are significantly different from 0 at the 10% sig- nificance level. The one-degree interaction terms of four variables and the quadratic interaction terms of seven variables have significant effects on the housing prices. This result provides strong evidence of implicit prices with complicated spatial distribution patterns. Table 3. Regression results of spatial expansion models Variables One-degree term model Quadratic term model Coeffi- cients t Coeffi- cients t Constant 10.698 *** 91.871 10.699 *** 67.515 ln(building age) −0.061 *** −3.765 −0.079 *** −3.247 Inner environment 0.022 * 1.649 0.029 *** 1.729 U(inner environment) 0.008 * 1.803 External environment 0.022 * 1.653 0.050 *** 2.616 U(external environment) −0.015 ** −2.526 Property management 0.036 *** 3.490 0.033 ** 2.267 V2(property management) −0.001 * −1.718 Sports facility 0.032 *** 4.034 0.055 *** 4.131 V2(sports facility) −0.001 * −1.877 V(nearby university) 0.007 * 1.792 Living facility 0.032 *** 3.043 U(living facility) −0.007 ** −2.445 −0.010 ** −1.984 Education facility 0.050 ** 2.461 U2(education facility) −0.003 ** −2.471 Nearby subway −0.209 *** −3.208 U(nearby subway) 0.053 *** 2.587 V(nearby subway) 0.018 ** 2.387 0.081 *** 3.232 UV(nearby subway) −0.013 ** −2.493 Traffic condition −0.005 *** −3.585 −0.004 ** −2.037 U(traffic condition) 0.001 * 1.818 V(traffic condition) 0.001 *** 3.682 0.001 * 1.952 ln(distance to the Wulin Square) −0.087 * 1.786 −0.168 ** −2.149 Uln(distance to Wulin Square) 0.033 ** 2.212 0.128 *** 3.099 Vln(distance to Wulin Square) 0.019 * 1.898 U2ln(distance to Wulin Square) −0.021 ** −2.547 ln(distance to the West Lake) −0.269 *** −7.596 −0.336 *** −6.557 Vln(distance to the West Lake) −0.022 ** −2.413 V2ln(distance to the West Lake) −0.008 * −1.648 ln(distance to the Qianjiang New Center) −0.185 *** −4.028 −0.237 *** −3.061 Uln(Distance to the Qianjiang New Center) −0.015 * −1.716 −0.076 ** −2.505 U2ln(distance to the Qianjiang New Center) 0.017 *** 3.134 AICc −605.089 −657.128 Adjusted R2 0.671 0.704 Note: ***,**, and * represent significance at the 1%, 5%, and 10% levels, respectively. ===== PAGE 9 (score 39, numeric-paren 14, table-words 8, var-words 9) ===== Spatial heterogeneity in implicit housing prices: evidence from Hangzhou, China 23 The results of the two spatial expansion mod- els confirm that spatial heterogeneity exists in the implicit prices of the housing characteristics of the Hangzhou market. For example, the variables of inner environment, external environment, nearby subway, and building age are insignificant in the traditional hedonic price model, but their interac- tion terms are significant in Models 2 and 3. This result indicates the influence of the four variables on housing price and their tendency to still change over space. No significant residual dependence on a 0.01 level is detected by the Moran’s I, which indi- cates spatial expansion models can capture the spa- tial effect and be used to improving the misspecifi- cation problem, which lead to inefficient parameter estimations in the traditional hedonic price model. 4.3. Geographically weighted regression model With a Gaussian kernel, CV determines an opti- mal adaptive bandwidth that includes 182 obser- vations. Sensitivity analysis with alternative ker- nels (i.e. bi-square kernel) shows no significant dif- ferences. The values of VIF of all variables are less than 5, which do not suggest a problem of collin- earity among the independent variables. Table 4 shows the regression results of Model 4 (GWR). The adjusted R2 is 0.757, which is significantly better than that in the traditional hedonic price model and the two spatial expansion models. This improvement reflects that the GWR model can ef- fectively explain the relationship between housing prices and the explanatory variables and provide strong evidence that spatial heterogeneity plays an important role in the Hangzhou housing mar- ket. The GWR parameter estimates, which vary at each observation point, are described by their minimum, median, and maximum values, as well as by their interquartile range. For example, the lower quartile of the regres- sion coefficients of the distance to the West Lake is −0.421 and the upper quartile is −0.171. These values indicate that in a certain space location, the distance to the West Lake increases by 1% and the housing prices decline by 0.421%. Meanwhile, in another space location, the distance to the West Lake increases by 1% while the housing prices decline by 0.171%. The magnitude of change is 0.25%. One advantage of GWR is that the spatial patterns of the parameter estimates can be eas- ily mapped and visualized. Figure 1 reveals the spatial effect of the distance to the West Lake on housing price. Almost all samples reach the signifi- cance level of 1% by P value. Hence, the distance to the West Lake has an important influence on the housing prices throughout the entire study area. As expected, the estimates are negative and exhibit localized spatial patterns. The highest es- timates are found within North Hangzhou, where the housing prices are relatively lower than that in other areas, resulting in the rapid decrease of the price gradient of the distance to the West Lake. The estimates are the smallest and exhibit Table 4. Results of GWR model Variables Min Lwr Quartile Median Upr Quartile Max Constant 5.373 9.804 10.520*** 10.848 12.687 ln(building age) −0.180 −0.107 −0.061** −0.024 0.006 Inner environment −0.034 0.029 0.043** 0.066 0.097 External environment −0.042 −0.005 0.015* 0.028 0.103 Property management −0.015 0.006 0.016*** 0.026 0.051 Sports facility −0.019 0.015 0.028*** 0.043 0.076 Nearby university −0.104 −0.015 0.015*** 0.050 0.210 Living facility −0.087 −0.017 0.012*** 0.047 0.092 Education facility −0.068 −0.015 0.010*** 0.047 0.155 Nearby subway −0.170 −0.004 0.021** 0.048 0.164 Traffic condition −0.009 −0.004 −0.002*** 0.000 0.005 ln(distance to Wulin Square) −1.295 −0.151 −0.034*** 0.124 1.159 ln(distance to the West Lake) −1.224 −0.421 −0.280*** −0.171 0.083 ln(distance to the Qianjiang New Center) −1.317 −0.272 −0.131*** 0.082 2.775 AICc −714.328 Adjusted R2 0.757 Note: ***,**, and * represent significance at the 1%, 5%, and 10% levels, respectively. ===== PAGE 10 (score 26, numeric-paren 0, table-words 9, var-words 8) ===== H. Wen et al. 24 relatively smooth spatial trends within Central Hangzhou (the eastern region of the West Lake), which belongs to the traditional downtown area with convenient public facilities. The housing pric- es in this area are relatively high. In other words, the GWR model shows that the implicit prices of 13 housing characteristics are not entirely fixed in space but exist with spatial heterogeneity. These results verify that the global/average estimation by the traditional hedonic price model may be flawed. Model 5 is the MGWR. Compared with the GWR model, the MGWR model divides independ- ent variables into two types: global variables with fixed estimated coefficients (see Table 5) and lo- cal variables that change over space (see Table 6). Following the test statistic of Leung et al. (2000a), we find that four independent variables in the study are global variables while the remaining nine variables are local variables. Again, applying a Gaussian kernel function, CV results in an opti- Fig. 1. P value and regression coefficients for the distance to the West Lake variable Table 5. Regression results for global variables Variables Coefficients t value Critical value (10%) Critical value (5%) Inner environment 0.048 4.176 1.648 1.965 Nearby university 0.040 2.635 Sports facility 0.021 3.246 Property management 0.012 1.722 Table 6. Regression results for local variables Variables Min Lwr Quartile Median Upr Quartile Max Constant 3.401 9.887 10.354 10.879 13.094 ln(building age) −0.214 −0.113 −0.079 −0.030 0.033 External environment −0.055 −0.006 0.015 0.031 0.109 Living facility −0.107 −0.016 0.011 0.051 0.105 Education facility −0.094 −0.015 0.025 0.045 0.194 Nearby subway −0.205 −0.013 0.007 0.042 0.254 Traffic condition −0.011 −0.004 −0.002 0.000 0.005 ln(distance to Wulin Square) −1.739 −0.160 −0.003 0.120 1.515 ln(distance to the West Lake) −1.328 −0.403 −0.307 −0.142 0.142 ln(distance to Qianjiang New Center) −1.594 −0.279 −0.069 0.072 3.862 AICc −756.902 Adjusted R2 0.766