이상치 검출 및 그 영향에 관한 연구－ 주거실태조사의 주거환경 만족도평가를 대상으로 －

A Study on the Detection and Impact of Outliers: Focused on the Evaluation of Residential Satisfaction in Housing Survey

This study analyzed outliers which give a significant impact on reliability in the current Big Data era. We used the Housing Condition Survey (HCS) by the Ministry of Land, Infrastructure and Transport in Korea as a main dataset. We focused on the residential satisfaction of the respondents, detected the outliers, and performed an empirical analysis for impact factors. Although we used the Mahalanobis distance method, which is a common method for outlier detection, we found that this outlier detection method was unreliable. Alternatively, the Naive Bayes Classification method was utilized to detect the outliers and to verify the impact factors. This choice of method was based on the fact that the high correlation among the demographic characteristics and residential satisfaction of respondents are critical elements in the Naive Bayes Classification. The findings include that firstly, about 2,400 samples (12% of total) of the 2014 Housing Condition Survey were detected as outliers. Secondly, it was observed that the tendency of positive over-estimation about questions from the residential satisfaction of respondents in HCS is common. Thirdly, in order to reduce the occurrence of outliers in HCS, it is necessary to lessen the stress of respondents by avoiding long questions in table form.