Changes in core network size in Japan: Comparisons between the 1990s and 2010s

Few studies have examined changes in network size during the past 20 years in Japan despite changes in many other aspects of Japanese society that could affect Japanese social relationships. I conducted a time-series cross-sectional survey to investigate changes in network size for married Japanese people from 1993 to 2014. Results follow: 1) core network sizes decreased slightly; 2) the number of married males with no core network outside their households increased slightly; 3) kin and neighbour network sizes decreased and friend network size increased among married females; 4) kin network size decreased among married males; and 5) the probability of younger married males having no network friends increased. Overall, changes in network sizes were small, and we cannot conclude that serious social decay occurs among married Japanese people.