Bookmark the permalink. The Black-White IQ gap Increases when SES Levels Increase

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The Black-White IQ gap Increases when SES Levels Increase

Jan1 by 猛虎

Environmentalists wrongly believe that increases in the level of SES (i.e., socio-economic status) tend to reduce the black-white difference in IQ for which, to recall, it has certainly not decreased. Several works tend to confirm the pattern of an increasing gap.
From Herrnstein and Murray (1994, pp. 287-288), we have :

Second version: As blacks move up the socioeconomic ladder, do the differences with whites of similar socioeconomic status diminish? … The rationale goes like this: Blacks score lower on average because they are socioeconomically at a disadvantage in our society. This disadvantage should most seriously handicap the children of blacks in the lower socioeconomic classes, who suffer from greater barriers to education and occupational advancement than do the children of blacks in the middle and upper classes. As blacks advance up the socioeconomic ladder, their children, less exposed to these environmental deficits, will do better and, by extension, close the gap with white children of their class.

The pattern shown in the figure is consistent with many other major studies, except that the gap flattens out. In other studies, the gap has continued to increase throughout the range of socioeconomic status. [43]

From Jensen (1998, pp. 358, 469), we have :

From Gottfredson (2003, Table 2), we have :

Now, even the General Social Survey data confirms this pattern.
I use here the “Multiple Regression Program” since the dependent variable is not a dichotomous one. The logic behind this is that the coefficient will be greater (or smaller) if the IQ gap increases (or decreases). Because I want to restrict the sample to whites and blacks, RACE is recoded as follows : RACE(1-2) where 1 = whites, 2 = blacks. The variable used as a measure of IQ is the WORDSUM (a 10-items vocabulary test). To recall, vocabulary correlates with g at 0.83. The two following variables are used in order to determine the SES level : DEGREE (where 0 = Less than high school, 1 = High school, 2 = Junior College, 3 = Bachelor, 4 = Graduate) and REALINC (family income in constant dollar).
The variables used for the first run :
Dependent : wordsum
Independent : race(1-2)
Independent : age
Selection Filter(s) : degree(0) realinc(0-10000)

Allocation of cases (unweighted)
Valid cases = 2,366
Cases excluded by filters or weight = 49,020
Cases with invalid codes on variables in the analysis = 3,701
Total cases = 55,087

And for the second run :
Selection Filter(s) : degree(4) realinc(20000-160000)

Allocation of cases (unweighted)
Valid cases = 1,344
Cases excluded by filters or weight = 52,124
Cases with invalid codes on variables in the analysis = 1,619
Total cases = 55,087

The coefficient for RACE (recoded) is greater for the group with higher levels of education and family income in constant dollar. Or to put it another way, the relationship between race and wordsum is more negatively correlated for the group with high SES levels. This adds an additional support to Jensen and Herrnstein & Murray’s findings. This phenomenon is well understood in terms of regression to the mean. See, Murray (1999, Figure 3).
 

 

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