The 1932 data described in the article is important because it covered nearly the entire population of a country for a particular age group -- uneven data collection could not have skewed the results. Uneven data collection is the great enemy of psychological public policy, since politicians can so conveniently project their dispute onto the people that were not sampled. The 1932 Scotland data slams that door shut.

Other testing programs since then have showed a slow, steady rise in the average IQ, called the Flynn effect. However the relative shapes of the male and female histograms have been quite constant. (Ditto for the relative shapes of the racial curves.)