# RECORD 67d132eca470e26b7a8c41462ca1252d056a93bb # TITLE: Spatial and Social Media Data Analytics of Housing Prices in Shenzhen, China # YEAR: 2016.0 VENUE: PLoS ONE DOI: 10.1371/journal.pone.0164553 # AUTHORS: Chao Wu; Xin-Yue Ye; F. Ren; Y. Wan; Peng-Fei Ning; Qingyun Du # PAGES: 19 CANDIDATE TABLE PAGES (1-based): [6, 13, 14] # ABSTRACT: Housing is among the most pressing issues in urban China and has received considerable scholarly attention. Researchers have primarily concentrated on identifying the factors that influence residential property prices and how such mechanisms function. However, few studies have examined the potential factors that influence housing prices from a big data perspective. In this article, we use a big data perspective to determine the willingness of buyers to pay for various factors. The opinions and geographical preferences of individuals for places can be represented by visit frequencies given different motivations. Check-in data from the social media platform Sina Visitor System is used in this article. Here, we use kernel density estimation (KDE) to analyse the spatial patterns of check-in spots (or places of interest, POIs) and employ the Getis-Ord Gi* method to identify the hot spots for different types of POIs in Shenzhen, China. New indexes are then proposed based on the hot-spot results as measured by check-in data to analyse the effects of these locations on housing prices. This modelling is performed using the hedonic price method (HPM) and the geographically weighted regression (GWR) method. The results show that the degree of clustering of POIs has a significant influence on housing values. Meanwhile, the GWR method has a better interpretive capacity than does the HPM because of the former method’s ability to capture spatial heterogeneity. This article integrates big social media data to expand the scope (new study content) and depth (study scale) of housing price research to an unprecedented degree. ===== PAGE 1 (score 3, numeric-paren 0, table-words 0, var-words 3) ===== RESEARCH ARTICLE Spatial and Social Media Data Analytics of Housing Prices in Shenzhen, China Chao Wu1, Xinyue Ye5, Fu Ren1,2,3, You Wan1,2,3, Pengfei Ning1, Qingyun Du1,2,3,4* 1 School of Resources and Environmental Science, Wuhan University, Wuhan, China, 2 Key Laboratory of GIS, Ministry of Education, Wuhan University, Wuhan, China, 3 Key Laboratory of Digital Mapping and Land Information Application Engineering, National Administration of Surveying, Mapping and Geoinformation, Wuhan University, Wuhan, China, 4 Collaborative Innovation Center of Geospatial Technology, Wuhan University, Wuhan, China, 5 Department of Geography, Kent State University, Kent, Ohio, United States of America * qydu@whu.edu.cn Abstract Housing is among the most pressing issues in urban China and has received considerable scholarly attention. Researchers have primarily concentrated on identifying the factors that influence residential property prices and how such mechanisms function. However, few studies have examined the potential factors that influence housing prices from a big data perspective. In this article, we use a big data perspective to determine the willingness of buyers to pay for various factors. The opinions and geographical preferences of individuals for places can be represented by visit frequencies given different motivations. Check-in data from the social media platform Sina Visitor System is used in this article. Here, we use kernel density estimation (KDE) to analyse the spatial patterns of check-in spots (or places of interest, POIs) and employ the Getis-Ord G i method to identify the hot spots for different types of POIs in Shenzhen, China. New indexes are then proposed based on the hot-spot results as measured by check-in data to analyse the effects of these locations on housing prices. This modelling is performed using the hedonic price method (HPM) and the geo- graphically weighted regression (GWR) method. The results show that the degree of clus- tering of POIs has a significant influence on housing values. Meanwhile, the GWR method has a better interpretive capacity than does the HPM because of the former method’s ability to capture spatial heterogeneity. This article integrates big social media data to expand the scope (new study content) and depth (study scale) of housing price research to an unprece- dented degree. Introduction Residential property is a multidimensional and durable commodity, and its value is determined by a combination of characteristics categorized as structural, locational and neighbourhood attributes [1–3]. However, these attributes do not have individual market prices. Numerous studies have explored the relationships between housing prices and specific attributes by PLOS ONE | DOI:10.1371/journal.pone.0164553 October 26, 2016 1 / 19 a11111 OPEN ACCESS Citation: Wu C, Ye X, Ren F, Wan Y, Ning P, Du Q (2016) Spatial and Social Media Data Analytics of Housing Prices in Shenzhen, China. PLoS ONE 11 (10): e0164553. doi:10.1371/journal. pone.0164553 Editor: Kim-Kwang Raymond Choo, University of Texas at San Antonio, UNITED STATES Received: May 26, 2016 Accepted: September 8, 2016 Published: October 26, 2016 Copyright: © 2016 Wu et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability Statement: POI data are from http://open.weibo.com/. We used Open API interface to get check-in data. The relevant data are within the paper and its Supporting Information files. Attributes of house data are from http://sz. fang.com/. The relevant data are within the paper and its Supporting Information files. Housing price data are from Shenzhen Research Centre for Digital City Engineering. Interested readers and researchers can contact with Shenzhen development research center using the 284158541@qq.com. Interested readers and researchers can cooperate with Shenzhen ===== PAGE 6 (score 29, numeric-paren 0, table-words 3, var-words 19) ===== or fake users [45]. We filter the check-in data using the following critera (i) the location of a check-in is not in Shenzhen based on the geographical location; (ii) the name of the POI is not correct based on the text discriminant; (iii) we believe that users who have only one check-in record are not valid users and that their behaviours are accidental in a given time period(July 2014 and June 2015 in this article); (iiii) and based on the third criterion, we filter valid POIs that are signed by at least one valid user. Finally, we acquire 447,778 check-in records from 216,165 users and 22,670 POI. To ensure the privacy of personally identifiable information (PII) [46], we do not identify the information of users. This article uses 13,268 CBF sites and 1,413 GRE sites identified by researching the locations and names of POIs based on the Code for Classification of Urban Land Use and the Planning Standards of Development Land [47]. The CBF includes commercial facilities, business facilities, entertainment and sports facilities, and public utility outlets, and the GRE consists primarily of parks, green belts and urban squares. POI types and aggregated information can be seen in Table 2. Methods Spatial hot-spot analysis method based on check-in data In this section, we present our proposed method for using check-in data to detect hot spots. Each check-in record includes the user ID, time, coordinates (longitude and latitude), POI ID, Table 1. Measurement methods and housing characteristic variable signs. Variable Variable definition and measurement methods Mean Std.dev. Expected sign Structural Variables Area Square footage of the living area of house (m2) 100.487 35.689 + Floor Floor on which the unit is situated (floor) 18.018 10.067 + NumBed Number of bedrooms in unit 3.139 0.965 + NumWash Number of bathrooms in unit 1.725 0.643 Unknown Fee Property management fees (RMB) 3.868 1.069 + RPlot Ratio of floor area 3.976 1.404 - RGreen Ratio of green space area (%) 0.345 0.0729 + Locational Variables DCBD Distance to CBD (central business district; km) 23.339 10.208 - DSub Distance to nearest metro station (km) 0.319 0.409 - DBus Distance to nearest bus station (km) 0.019 0.023 - DHospital Distance to nearest hospital (km) 0.122 0.786 Unknown DSnursery Distance to nearest nursery school (km) 0.597 0.464 - DSprimary Distance to nearest primary school (km) 0.756 0.464 - DSmiddle Distance to nearest middle school (km) 0.108 0.640 - DPark Distance to nearest park(km) 0.113 0.609 - Neighbourhood Variables GiZScore_G Degree of activity in green space 0.438 2.308 - GiZScore_C Degree of activity in commercial centre 1.181 3.229 - doi:10.1371/journal.pone.0164553.t001 Table 2. POI types and aggregated information. Type Abbreviation Counts Percentage Commercial and business facilities CBF 13,268 59% Industrial IND 890 3.93% Transport facilities TRA 1,696 7.48% Residence communities RES 3,569 15.74% Green space GRE 1,413 6.23% Administration and public services APS 1,834 8.09% Total 22,670 100% doi:10.1371/journal.pone.0164553.t002 Analytics of Housing Prices PLOS ONE | DOI:10.1371/journal.pone.0164553 October 26, 2016 6 / 19 ===== PAGE 7 (score 5, numeric-paren 0, table-words 0, var-words 5) ===== and name and category of the venue. We use address-coding technology to locate records for our database and detect hot spots using the number of check-ins, which are obtained from POI data [48]. The POI data include the POI ID, coordinates, check-in totals, user counts and cate- gories. We measure the hot spots by identifying their relationship with different types of POIs and exploring the effects of CBF and GRE. Before detecting the hot-spot status of the different types of POIs, we analyse the overall spatial patterns. The kernel density estimation (KDE) is used to analyse the spatial distribution of all check-in POI data. KDE attempts to produce a smooth density surface of spatial point events in geographic space [49]. The general form of a kernel density estimator is given by f ðsÞ ¼ Xn i¼1 1 ph2 k dis h   ð1Þ where f(s) is the KDE function at location s, h is the bandwidth of the KDE, dis, is the distance from point i to location s, and the function k (called the kernel function) represents the spatial weight function of the ratio between dis and the bandwidth h. Briefly, the results of the KDE rely on kernel sizes (called the search radius) and grid sizes. In this analysis, first, individual output cells were partitioned in 100m100m areas, which can provide greater precision in the estimation most efficiently. Because too small of a grid size can increase the computational cost, whereas too large of a size can result in important details being ignored. Second, we select a search radius of 1000 m based on multiple testing rounds. Thresholds of less than 1000m, such as 600m and 800m, make the density distribution focus on a limited extent of elemental points, and the overall characteristic are not obvious. Conversely, thresholds of greater 1000m, such as 1200m and 1500m, make the density distribution overly smooth, and local differences cannot be well represented. We set 1000 m as the ideal threshold because it is the longest dis- tance that remains comfortable to travel on foot (10–15 minutes) and obtains relatively good results in this paper. After kernel density analysis, we rank the POIs based on the counts of check-ins and users for all check-in spots to detect the POIs that are popular. The power-law distribution patterns (Fig 2) show that there are far more POIs with fewer check-ins and users than POIs with many check-ins and users. The patterns are similar to those in a previous study [33]. The results of Fig 2 suggest that POIs with high popularity, represented by the numbers of check-ins and users, provide more attractions to residents and are better known to people. Differences in peo- ples’ preferences and usages for POIs reveal that the formation of hot spots and cold spots for POIs is reasonable. We apply the ‘average nearest neighbour’ index to judge whether the spatial distribution of points is clustered or dispersed. This process is conducted for GRE and CBF separately. The clustering patterns of GRE and CBF are used to determine whether they are hot spots. Because of the discrete distribution of points and simplification of the amount of big data [50, 51], we use grids to replace points to analyse the spatial patterns [52]. First, we divide the study area into 500 m x 500 m spaces and then apply the grid. Testing determined that 500 m is the optimal choice because a grid size larger than 500 m tends to mask local differences and because a grid size smaller than 500 m can exaggerate local characteristics. We then calculate the total number of check-in records and the number of POIs for each grid. We explore the possible hot spots using the grids and then use Getis-Ord G i to identify the hot spots. The Getis-Ord G i statistical clustering method [53, 54] is used to detect significant clusters of high value within a city according to locations that contain many people. Getis-Ord G i is a local sta- tistic used to assess each feature within the context of neighboring features. This article defines a ‘hot spot’ as a place with a high degree of activity. The statistics are calculated as follows: Analytics of Housing Prices PLOS ONE | DOI:10.1371/journal.pone.0164553 October 26, 2016 7 / 19 ===== PAGE 13 (score 30, numeric-paren 1, table-words 8, var-words 9) ===== with the findings of previous studies [58–60]. The structural attributes, such as the number of washrooms, floor height, area, property management fees and green ratio, all have effects on housing prices and add 9.4%, 6.3%, 29.3%, and 2.3%, respectively, of extra value to the price of housing with a 1- unit increase. The effects of location variables are similar as expected with the exception of distance to primary schools. A 1- km increase in the distance to parks, hospi- tals, bus stations and subway stations reduces housing prices by 11.1%, 9.4%, 4.9% and 4.9%, respectively. Primary schools are an exception because of the policy of school district housing in China. The effect of school location on housing prices is determined by distance as well as school quality. Geographicallyweighted regression results. The results of the local regression analysis (GWR) are summarized in Table 5. As previously mentioned, this method evaluates spatial variations in the relationships between the variables and housing prices. In this model, the R2 value increases from 0.724 (HPM) to 0.9399 (GWR), thereby showing that the GWR method has a better interpretive capability than the HPM. The GWR can explain 93.99% of the varia- tion according to the R2 value. We also measure the spatial auto-correlation (Moran’s I index = 0.041, z-score = 3.86) by calculating Moran’s I index for the residuals of the GWR to ensure that the validity of the model for the residuals is random. Additionally, the AICc of the GWR is -74703.46207, and the bandwidth equals 0.337, which are less than that of the HPM (AICc = -36082.16912). The difference in the AICc of greater than 3 suggests that the GWR is more representative of reality [56]. Table 5 shows that all the variables are significant at 1% or 5% with the exception of DPark (p-value = 0.855). Additionally, the outstanding achievement of the GWR method is its ability to visualize local parameters. Fig 7 presents the GiZscore_C and GiZscore_G. Because of the discrete distribution of points, we use the inverse distance weighted (IDW) interpolation method to obtain a better visual effect. The output cell size of the IDW processes is set to 100 m, and a natural breaks (Jenks) classification is applied. Con- sidering that the coefficientshave positive and negative values, we set a zero value as a class limit to distinguish the positive and negative effects. Table 4. Hedonic price method (HPM) parameter estimate summary. Explanatory variable Estimated coefficient t-ratio p-value Constant 0.060 19.388 .000*** DCBD -0.326 -55.863 .000*** Fee 0.293 43.604 .000*** DPark -0.111 -27.376 .000*** NumWash 0.094 21.743 .000*** GiZScore_C 0.083 17.104 .000*** DHospital -0.094 -24.942 .000*** SPrimary 0.080 21.966 .000*** Floor 0.063 20.077 .000*** GiZScore_G 0.134 24.466 .000*** DBus -0.049 -14.273 .000*** DSub -0.049 -11.417 .000*** Area 0.031 6.907 .000*** RGreen 0.023 6.854 .000*** R2 0.724 *** Significant at the 1% level. doi:10.1371/journal.pone.0164553.t004 Analytics of Housing Prices PLOS ONE | DOI:10.1371/journal.pone.0164553 October 26, 2016 13 / 19 ===== PAGE 14 (score 25, numeric-paren 1, table-words 3, var-words 9) ===== The regression coefficientfor GiZscore_C is greater than zero because major concentrations are observedin Futian, Longhua, central and northeast Nanshan, the southern part of Bao’an and Guangming and central Dapeng. The CBF is more strongly clustered, which is associated with more check-ins, and the housing prices are higher in these locations, which represent the most prosperous areas of each district and have more complete facilities and more workplaces. These areas provide convenient amenities to housing buyers, such as employment, cafes, shop- ping and entertainment. Therefore, the housing prices are high. However, Fig 7(a) presents unexpectedresults for Longgang, Luohu and Yantian, with lower housing prices despite the greater clustering (with more check-ins) of the commercial and business facilities. GiZscore_C Table 5. Geographically weighted regression (GWR) parameter estimate summary. Explanatory Variable Minimum Lower quartile Median Upper quartile Maximum p-value Constant -12.8186 -1.38137 -0.2675 0.04614 10.28509 .000*** Floor -0.35291 0.031246 0.040169 0.056628 0.339561 .000*** NumBed -0.66773 -0.02149 0.040887 0.128011 0.493299 .000*** NumWash -0.64065 -0.0432 0.022523 0.06847 0.358014 .000*** Area -0.68338 -0.01717 0.074358 0.142633 1.335995 .000*** RPlot -10.9418 -0.5452 -0.1074 0.145695 1.900368 .000*** RGreen -3.84742 -0.0312 0.089782 0.399657 1.858314 .000*** Fee -2.68112 0.015945 0.25459 0.621551 4.052185 .000*** DSub -12.302 -0.40319 -0.02085 0.563174 15.22164 .000*** DBus -4.17797 -0.35394 -0.03028 0.509983 23.5197 .004** DSnursery -18.9376 -0.1124 -0.03278 0.158163 4.604339 .000*** DSprimary -12.4242 -0.13258 0.017652 0.261109 2.282185 .000*** DSmiddle -3.55686 -0.41095 0.017384 0.249635 14.10076 .000*** DHospital -4.868 -0.62254 -0.12827 0.300655 5.447187 .000*** DPark -2.27624 -0.07367 0.012992 0.328673 11.93626 .855 DCBD -16.3229 -0.74499 -0.09705 0.430907 1.94271 .000*** GiZScore_G -11.9198 -2.41877 -0.1252 0.179357 4.508242 .000*** GiZScore_C -9.16523 0.015567 0.463302 2.229864 11.68491 .000*** R2 0.9399 Bandwidth 0.337 ***, ** Significant at the 1% and 5% levels, respectively. doi:10.1371/journal.pone.0164553.t005 Fig 7. Spatial variation of the local parameters of the GWR. (a) and (b) are GiZscore_C and GiZscore_G, respectively. doi:10.1371/journal.pone.0164553.g007 Analytics of Housing Prices PLOS ONE | DOI:10.1371/journal.pone.0164553 October 26, 2016 14 / 19 ===== PAGE 15 (score 12, numeric-paren 0, table-words 2, var-words 8) ===== has a negative effect on housing prices, and because of the development of Futian and Nan- shan, the position of Luohu has been declining. Luohu is an old urban district that is currently facing the problem of an old-age demographic bump. Senior citizens tend to choose housing in locations with a good environment characterized by peace and quiet. The clustering of resi- dents can cause noise and traffic jams, which may affect the residents’ daily lives and rest. Yan- tian has relatively poor traffic conditions and no subway system. Thus, the clustering of CBF in Yantian may result in worse traffic conditions. Similarly, GiZscore_C has a negative effect on housing prices in Yantian. Longgang is a relatively poorly developed area in Shenzhen and has comparatively low housing prices. Housing buyers in Longgang pay more attention to trans- portation and the convenience of getting to work. Thus, it is not difficultto imagine that GiZs- core_C would have a negative effect on housing prices in Longgang. The GWR model reveals that the relationship between GiZscore_G and housing prices is not stationary across the study area, as illustrated in Fig 7(b). Most major areas show a positive effect of GiZscore_C on housing prices, with the exception of the south of Bao’an, the west and centre of Longgang, and most of Yantian. Yantian was the first ‘national biome’ in South China, and the air quality is good, which attracts many people. However, Yantian’s traffic con- ditions are relative poor, and it is located in a fault zone in Shenzhen. Therefore, it is likely that people prefer to visit this scenic spot for recreational purposes rather than live there. Conclusions This article suggests a framework for applying a GWR model and a big data perspective for evaluating the influence of urban hot spots on housing prices in Shenzhen, China. This work contributes to the field of housing price research by identifying POI hot spots through the anal- ysis of check-in data and by exploring the influence of a POI’s degree of activity (from the perspective of popular perception) on housing prices. Despite the widespread use of crowd- sourced geographic data (CSGD) [49, 61–64], few studies have used these data to examine housing prices, which are closely tied to public opinion and sentiments. We apply GWR method to test the hypothesis that hot spots (identified using check-in data) have significant effects on housing values. Our results are consistent with expectations. In this article, we intro- duce the use of check-in data, which represent a novel data source in the field of housing price research. Additionally, we take spatial heterogeneity into consideration and explore the factors that influence housing prices for different locations. Finally, we chose Shenzhen, China as our case study because housing prices in Shenzhen have skyrocketed in recent years, which is an area of continued concern [61]. This article integrates big social media data and expands the scope (new research content) and depth (study scale) of housing price research to an unprece- dented degree. This article applies the Getis-Ord G i technique to detect hot-spot areas of CBF and GRE. We then explore the relationship between housing prices and hot spots using hedonic price modelling and geographical regression modelling. The R2 of the HPM is 0.724, which indicated that the HPM can be used to analyse the effects of hot spots from a global perspective. CBF and GRE hot spots both increase housing prices. The R2 of the GWR is 0.9399, which indicates a stronger interpretive capability compared with the HPM. The results of the GWR reveal that the effects of influential factors vary over space, as represented by different coefficients. Finally, we select typical and special areas for our interpretation. Most of the data values require innovative methods of analysis to identify their potential uses [65]. Although this article provides a new perspective for the application of big social media data to the study of housing prices, it still has several limitations. Analytics of Housing Prices PLOS ONE | DOI:10.1371/journal.pone.0164553 October 26, 2016 15 / 19