Regional Differences in the Socio-economic and Built-environment Factors of Vacant House Ratio as a Key Indicator for Spatial Urban Shrinkage

The phenomenon of urban shrinkage is surging through cities in Japan. To understand the current situation of urban shrinkage in Japan, the number of vacant housing would be one of the key indicators. The purpose of the study is to clarify the regional differences in the socio-economic and built-environment factors of vacant house ratio as a key indicator for spatial urban shrinkage. The characteristics of cities are identified by means of socio-economic and built-environment factors, which enable us to describe the current situation of spatial urban shrinkage more precisely. In this analysis, 771 cities in Japan are original units in order to articulate the geographical differences in urban shrinkage. To differentiate regions, we classified cities according to urban employment area (UEA) into 4 categories. Using 7 socio-economic and built-environment variables, a general linear mixed model was employed to clarify the statistical significances in each UEA category. The key findings were as follows. First, strong trends of vacant house ratio and its factors among categories were found. Second, socio-economic factors affecting vacant house ratio in each category were statistically significant in all the categories. Third, builtenvironment factors also had a clear relationship with vacant house ratio, but the influences varied among the four categories. Finally, in order to prepare for future spatial urban shrinkage, areas of anticipated spatial urban shrinkage were identified from the results of the study.