Can the I.Q. tell us anything of practical importance? Is it
related to our commonsense notions about mental ability
as we ordinarily think of it in connection with educational
and occupational performance? Yes, indeed, and there is
no doubt about it. ... The I.Q. obtained after 9 or 10
years of age also predicts final adult occupational status to
almost as high a degree as it predicts scholastic perform-
ance. . . . The average I.Q. of persons within a particular
occupation is closely related to that occupation's standing in terms of average income and the amount of prestige ac-
corded to it by the general public [p. 9].