“…To measure age assortative mating, we calculated husband-wife age gap based on respondents' and their spouses' year of birth and respondents' gender. Following Verbakel and Kalmijn (2014), we grouped the husband-wife age gap, which ranged between -34 and 34, into five categories to capture age hypogamy, homogamy, and hypergamy: (1) husband younger than wife by 3 or more years ([-34, -3]), (2) husband-wife age difference within 2 years ([-2, 2], reference), (3) husband older than wife by 3 to 5 years ([3, 5]), (4) husband older than wife by 6 to 10 years ([6, 10]), and (5) husband older than wife by 11 or more years ([11, 34]). Among the respondents in the category of -34 to -3 (husband younger than wife by 3 or more years; age hypogamy), 55% had a husband-wife age gap of -3 years, and another 23% and 9%, respectively, had an age gap of -4 and -5 years, whereas the husband-wife gap of -34 represented only one extreme case in our sample.…”