Wal-Mart is only the latest in a long series of employers who have been hit with charges of discrimination on the basis of statistical differences among members of their workforce — differences between women and men in this case.

Back during the 1980s a similar charge was brought against Sears, even though no one could find a single woman in all the hundreds of Sears stores who had been discriminated against — just numbers that were different as between women and men.

When you broke down the numbers, it turned out that women were not equally represented among people who sold automotive equipment or construction materials. It also turned out that many women had no interest in selling automotive equipment or construction materials, and had turned down opportunities to do so.