Russel-Research-Method-in-Anthropology

Bivariate Analysis: Testing Relations 633
.50
Educational Homogamy
.45
.40
.35
.30
.25
.20
.15
0 1 2 3 4 5 6 7 8 9 10
Per Capita Energy Consumption (In)
Figure 20.5. The relation between per capita energy consumption and educational
homogamy is nonlinear.
SOURCE: J. Smits et al., ‘‘Educational Homogamy in 65 Countries: An Explanation of Differences in Openness
Using Country-Level Explanatory Variables,’’ American Sociological Review Vol. 63, pp. 264–285.
1998 by the American Sociological Association. Reprinted with permission.
(Homogamy means marrying someone who is similar to you, so educational
homogamy means marrying someone who has the same level of education as
you do.) The relation between the two variables is very clear: It’s an inverted
U.
You might think that the relation between these two variables would be linear—people
of similar education would be attracted to each other—but it isn’t.
Here’s how Smits et al. reckon the inverted U happens: People in nonindustrialized
countries rely mostly on agriculture, so family background (which
determines wealth) tends to be the main criterion for selecting mates. As
industrialization takes off, education becomes more and more important and
family background becomes less important for building wealth. Educated people
seek each other out to maximize their life chances.
Eventually, though, when countries are highly industrialized, education is
widespread, people have high wages, and there are social security systems.
People in those countries don’t have to rely on their children for support in
old age, so romantic love becomes the dominant force in mate selection and
the level of educational homogamy drops like a stone.
Here’s another one. Beginning with 5F and continuing up to 75F, the
mean number of assaults rises steadily with the average daily temperature in