<p>This is one gender gap that will appear never to close if we measure the gap with incomplete measures on the statistics. As theothermuse points out women are more free now to make their own choices. One of those choices is not to work or to work shorter hours. In my field there are no women who put in as many hours as I do. This is not always by their choice, although it is in most cases. Some do not have the spousal support to tolerate an 80 hour work week or to pick up the slack at home. In some of the higher paid areas in science the hours are long. The company or university is really paying for two people: the scientist and the spouse who picks up the slack. The women I know who are the happiest married wisely. It is not necessarily dependent upon where they work, probably because women are a little wiser at looking into some of these lifestyle issues before they sign on the dotted line.</p>