A couple of recent studies by Statistics Canada on the phenomenon of 'assortive marriage' have generated some comment. The point is easy enough to explain and it's not really hard to understand:
Changing role of education in the marriage market in Canada and the United States:
...54% of Canadian young couples had the same educational level in 2001. However, 33% of couples differed by one educational level, while only 12% of couples differed by two educational levels. Less than 2% of couples differed by more than two educational levels.
Educational homogamy has been rising mainly because intermarriage between adjacent education levels has been declining both at the top and bottom of the educational hierarchy.
Declining intermarriage between those with university degrees and those with less education was a major factor in both countries. In Canada, the rate of intermarriage between the university educated and those with only some post-secondary education fell by 38%; in the United States, the rate fell by 45%.
Similarly, the intermarriage rate between high school graduates and those who had completed less than high school fell by 30% in the United States and by 58% in Canada.
In another study, the changing composition of families is offered as an explanation for some of the increase in income inequality:
While this study does not investigate why family market-income inequality rose, one factor which likely plays a role in this is a widening inequality in family earnings (from wages, salaries and net self-employment income). A key driver of this is the rising earning power of the two-earner family, especially when both earners are highly educated. (Preliminary results suggest that individual earnings inequality is not driving this trend.)
While homogamy - I've never seen this word before, but it works for me - has no doubt been a contributing factor to income inequality, it's far from being even a partial explanation for the increase in inequality that we've seen in the past couple of decades. Those gains are concentrated in the top 1% of the income distribution and higher, and I doubt very much that there are that many power couples where each partner is pulling down $1m/yr.
But the longer-run implications for social mobility are disquieting. Parents' education levels are a good predictor for post-secondary education levels, and there's a strong link between education and income. This trend of increasing education-based homogamy will likely increase the correlation of income levels across generations.
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