"How is it that women make up approximately half of those earning their PhDs in the sciences and yet account for less than a quarter of full-time professors?"

Dear Dr. Duncan, What an excellent question. Might I suggest that you remember your scientific training and find some evidence as to the cause of this and not just assume that you know the answer based on a few anecdotes before you go charging in with more sexism but with a different bias?

How do we know that this is not due to choice rather than bias as people assume for nursing? Have you factored in the fact that more women tend to leave their careers to start and look after families? Science is unfortunately very hard to get back into if you take several years away since you have to catch up with the state of the art again and rebuild your research program.

As you should know scientists are convinced by good, high quality data and not a bunch of anecdotes and wild assumptions. You are a scientist so please act like one.