Social Science Statistics Blog

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21 September 2005

More on Affirmative Action

Felix Elwert

It's well known that African American college students on average (repeat: on average) have lower SAT scores than white students (see Bowen and Bok's book The Shape of the River). Now here's something that annoys me: Every now and then, I run into somebody who takes this observation as evidence that affirmative action dilutes academic standards. Hello? Differences in mean SATs among accepted students have little or nothing to do with affirmative action!!

Consider this: SAT scores are roughly normally distributed among both blacks and whites but the distribution for blacks is shifted a bit to the left (lower mean). Now consider a college that will admit every candidate above a certain cut-off point (same cut-off for everybody). Under these circumstances the average SAT score of accepted black students would be lower than the average SAT score among accepted white students, even though the college has applied a uniform, race-blind admission standard. Why? Because the tail area of the white SAT distribution extends farther to the right of the cut-off point than the tail area of the distribution for blacks, whatever the reason. Upshot: racial differences in test scores in a student body don't reveal whether a school practices affirmative action and by themselves certainly don't betray "diluted standards." In addition, more or less the only way to create a student body where black and white students have the same average SAT score, given these race specific SAT distributions, would be to set drastically higher admissions standards for blacks than for whites - i.e. to discriminate against blacks. Surely, that wasn't the point?

(This observation comes to me via friends of UCLA's Thomas Kane. Kane is now moving to Harvard - thus moving this blog closer to the source.)

Posted by James Greiner at 7:00 AM