How often do you know someone’s race but nothing else whatsoever about them?
It’s an additional piece of information and allows you to do more of an update. If black people, on the average, have lower IQs than white people, then (for instance) black people with college degrees are still likely to have lower IQs than white people with college degrees, even if college raises the likely IQ for both groups. It is also possible to have traits such that given those traits race is no predictor at all, but those would be balanced out—if race is no predictor of IQ among people with PhDs, it must be a stronger predictor for people without PhDs than it is for the general populace.
If black people, on the average, have lower IQs than white people, then (for instance) black people with college degrees are still likely to have lower IQs than white people with college degrees, even if college raises the likely IQ for both groups.
Not necessarily. You haven’t accounted for differences in variance between the two groups.
To make a very rough analogy: it seems widely believed that there is greater variance in intelligence among men than among women; surely such differences are imaginable among racial groups. (For one thing, there’s more genetic variation among Africans than among other human populations — which makes sense, given that all other human populations descended from small subsets of Africans.)
Nor for selection effects on who gets to go to college — for instance, there seem to be a lot of pretty dopey people who have unusual bonuses to their chances to get into college on account of their parents being wealthy.
Nor for socioeconomic differences in general, which are substantial between whites and blacks in America. To make another very rough analogy: If two people reach the same measurement of achievement, but one has to overcome greater obstacles to get there, we would often take this as an indicator that that person had greater ability: a runner who runs a five-minute mile while carrying ten pounds of lead weights is a better runner than one who makes the same achievement carrying no weight.
Not necessarily. You haven’t accounted for differences in variance between the two groups.
Yes I have—see the next comment. If blacks with college degrees don’t have lower IQs than whites with college degrees, and blacks in general have lower IQ, then blacks without college degrees must have even lower IQs so that the average is still lower IQ.
Furthermore, taking other factors into consideration can result in worse discrimination. Consider the trait that most obviously makes up for the difference—actually taking an IQ test. Blacks may have lower IQ than whites, but blacks who take an IQ test and score X don’t have lower IQ than whites who score X at all. But if I were to hire people based on the trait “scoring X on an IQ test”, and X is at the high end, I may end up hiring a lot more whites than blacks—a small difference in IQ translates to a large difference in the number of people at the tail end of the distribution. If people with IQ 145 are 10 times as common as people with IQ 150 and the black curve is only shifted by 5 points, and I want to hire people with IQ 150, I may end up hiring whites to blacks at a 10 to 1 ratio compared to the proportion of blacks who apply.
It’s an additional piece of information and allows you to do more of an update. If black people, on the average, have lower IQs than white people, then (for instance) black people with college degrees are still likely to have lower IQs than white people with college degrees, even if college raises the likely IQ for both groups. It is also possible to have traits such that given those traits race is no predictor at all, but those would be balanced out—if race is no predictor of IQ among people with PhDs, it must be a stronger predictor for people without PhDs than it is for the general populace.
Not necessarily. You haven’t accounted for differences in variance between the two groups.
To make a very rough analogy: it seems widely believed that there is greater variance in intelligence among men than among women; surely such differences are imaginable among racial groups. (For one thing, there’s more genetic variation among Africans than among other human populations — which makes sense, given that all other human populations descended from small subsets of Africans.)
Nor for selection effects on who gets to go to college — for instance, there seem to be a lot of pretty dopey people who have unusual bonuses to their chances to get into college on account of their parents being wealthy.
Nor for socioeconomic differences in general, which are substantial between whites and blacks in America. To make another very rough analogy: If two people reach the same measurement of achievement, but one has to overcome greater obstacles to get there, we would often take this as an indicator that that person had greater ability: a runner who runs a five-minute mile while carrying ten pounds of lead weights is a better runner than one who makes the same achievement carrying no weight.
Yes I have—see the next comment. If blacks with college degrees don’t have lower IQs than whites with college degrees, and blacks in general have lower IQ, then blacks without college degrees must have even lower IQs so that the average is still lower IQ.
Furthermore, taking other factors into consideration can result in worse discrimination. Consider the trait that most obviously makes up for the difference—actually taking an IQ test. Blacks may have lower IQ than whites, but blacks who take an IQ test and score X don’t have lower IQ than whites who score X at all. But if I were to hire people based on the trait “scoring X on an IQ test”, and X is at the high end, I may end up hiring a lot more whites than blacks—a small difference in IQ translates to a large difference in the number of people at the tail end of the distribution. If people with IQ 145 are 10 times as common as people with IQ 150 and the black curve is only shifted by 5 points, and I want to hire people with IQ 150, I may end up hiring whites to blacks at a 10 to 1 ratio compared to the proportion of blacks who apply.
Why would IQ matter more than academic and job performance?