分野別セミナー

In Japan, rates of numbers of divorce to that of marriage per year exceed one-third from 2000 onwards. This fact is frequently referred to as if one-third of marriaged couples will divorce in future. This interpretation is doubtful since numbers of marriage has been rapidly decreasing in Japan because of declining birth rates and, on the other hand, numbers of divorce include those of married couples from older generations with relatively high birth rates. What are true couple-wise divorce rates, that is, rates of couples married in a year who will divorce afterwards, in Japan? Estimates of these rates are important because short marriage durations will frequently result in children with insufficient parental cares and financial supports. In order to estimate couple-wise divorce rates, we have to forecast numbers of divorce in future for couples married each year. This can be done using methods to construct life table. From the database of Ministry of Health, Labour and Welfare of Japan, we got marriage durations for couples who divorced in 1947–2010 and estimated their marriage date at first. From thus obtained marriage and divorce years of each couples, we predicted numbers of future divorce of couples married in each year and finally predicted their couple-wise divorce rates. The result shows that actual couple-wise divorce rates will be over one-third for couples married from 1997 onwards, contradictory to our first hypotheses that actual couple-wise divorce rates are much less than one-third. Moreover, it will be almost 40% for those married in 2002.