That's the good news, according to two Cornell University economists. After making about 40 percent less than men for decades, women now make about 20 percent less, on average, say Francine Blau and Lawrence Kahn. The bad news is that a smaller portion of the gap can be explained by differences in education and work experience between men and women. People with more education naturally earn more than others; so do people with longer experience in their jobs. Women are coming closer to men in educational attainment and work experience, but they still don't make the same money.

The unexplained difference, the economists say, may be due to discrimination in hiring and raises. Discrimination is hard to put a finger on. But in this case it seems to fall under the Sherlock Holmes rule: When all the other possible explanations have been eliminated, the remaining explanation, no matter how unlikely, is the truth. They do note experiments done with real employers showing that, for certain jobs at certain businesses, women were less likely to be interviewed than men. But they end on an optimistic note -- for women, at least.

"Women's education has been rising relative to men's, and indeed among younger cohorts women are more likely to graduate college than men. This trend shows no sign of abating. And, technological change, which has raised women's wages through demand effects, will probably continue and could even accelerate."

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