Tuesday, August 18, 2009

Skin tone and IQ among blacks: The General Social Survey recorded the skin tone of 495 black respondents from very light brown (1) to very dark brown (5). I calculated correlations between this measure and a number of variables:

Correlation with light skin tone

Wordsum .16
Years of education .17
Father's years of education .12
Mother's years of education .20
Spouse's years of education .13

All positive, but small. Then again, this is crude measure of genetic variation. Measurement error lowers the correlation. So I do take this as evidence that genes help explain the race-IQ link since whether the individual is light-skinned or dark, what white folks see is a black person. If whites determine black outcomes, there should be no correlation with skin tone.

I also wanted to see if blacks were lighter in the North as I had read before. Here are the means:

Mean lightness of skin

West North Central 3.00
East North Central 2.98
West South Central 2.83
Middle Atlantic 2.78
East South Central 2.73
Pacific 2.62
South Atlantic 2.55

Blacks in the mid-Atlantic region do not have a high average, but those from Ohio to North Dakota do.

Black-white differences in glaucoma

Glaucoma is a progressive condition caused by a combination of genetic and environmental factors and is the leading cause of irreversible bl...