서초·강남 아파트가격이 비강남 지역 가격에 미치는 영향: 도구변수를 이용한 실증분석

초록

1. CONTENTS (1) RESEARCH OBJECTIVES This study estimates the effect of Seocho–Gangnam apartment prices on housing prices in the other 23 districts of Seoul, with a focus on identifying causal effects net of common macroeconomic and policy factors. (2) RESEARCH METHOD To address endogeneity arising from the simultaneous determination of Gangnam and non-Gangnam prices, we construct a Bartik shift-share instrumental variable based on the 2016 housing type composition in Seocho–Gangnam and quality-specific price changes observed outside this area. The model is estimated using two-stage least squares (2SLS) for the full sample period (2017–2025) and separately for pre- and post-COVID-19 subperiods. (3) RESEARCH FINDINGS For the full sample (2017–2025), OLS estimates show a 0.2–0.3 percent increase in non-Gangnam prices per 1 percent rise in Seocho–Gangnam prices, while 2SLS estimates yield elasticities close to 1, consistent across four Seoul subregions. After COVID-19, the instrument loses some explanatory power, yet 2SLS coefficients remain larger than OLS, confirming downward bias in OLS estimates. 2. RESULTS Rising Seocho–Gangnam apartment prices lead to significant increases in non-Gangnam housing prices across all subregions of Seoul. The gap between OLS and 2SLS estimates indicates the presence of downward bias in OLS, which becomes more pronounced in the post-COVID-19 period. These findings suggest that evaluating housing market spillovers without addressing endogeneity leads to systematic underestimation of price transmission effects.

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