Only the first of those four articles deals with women in IT jobs. It is behind a paywall but I found a freely available copy here:
http://www.mcgill.ca/files/economics/leavescience_all.pdf . It's a nice article. I don't think it supports laying the blame on sexism, though.
The paper focuses on something called the "exit rate", that is, how many people with a certain education are working at a job unrelated to their education. The average exit rate over all professions and both genders is 21%. Female engineers have a pretty low exit rate of 12.9% - that is, 12.9% of women who studied engineering now work in other areas. Male engineers, on the other hand, have an extremely low exit rate of 9.8%.
The author then tries to explain the difference between "pretty low" for women and "extremely low" for men. She observes that the differentials in exit rate, across all fields including engineering, can be mostly predicted by the gender makeup of the field. Quote from the paper's conclusion:
> The results would appear to point to problems for women specic to the engineering
profession. However, I show that the excess exits of women trained as engineers, as well
as their excess exits for pay and promotion reasons, are no larger than would be expected
given the share of men in the field: the higher the male share, the greater the excess female
exits from the field, both in total and for pay and promotion reasons.
Then the author hypothesizes that improving mentoring and reducing "possible discrimination" might help reduce the gap, without giving any specific arguments.
It seems to me that the really important figure in the paper is 9.8%, not 12.9%-9.8%. That is, more males are behaving abnormally by staying programmers despite possible problems with pay and promotion, while the behavior of female engineers is closer to the average rational human being. What do you think?
Also, I'd be really interested in seeing what you think are the best papers proving that the lack of women of IT is due to sexism. Taking apart random vaguely related papers is fun, but I don't have infinite time.