Why are there three times as many male bloggers as female ones? Dave Munger runs the numbers:
In the aggregate, it seems clear that women are—whether actively or tacitly—discouraged from blogging about science. Aside from a few superstars like Skloot (who is in such demand that she’s been on a non-stop international book tour for the better part of a year), I’ve seen little evidence to convince me otherwise. Despite the fact that women are getting science PhDs in nearly the same numbers as men, they are blogging much less. I even looked at the average number of posts about peer-reviewed research they had done, and again, men outpaced women by nearly 50 percent, which means men may have written as many as 80 percent of the posts on ResearchBlogging.org. Even more strikingly, women may be discouraged from pursuing academic careers at all—from 1999 to 2003, 32 percent of chemistry PhDs were women, but only 18 percent of applications to tenure-track positions came from women.
(HT Razib Khan).