Stanford award winning economist, Professor Thomas Sowell, explains that because in general women choose careers that pay less well than the careers men choose, there is a pay gap in the average wage for men and women

Sowell explains that women choose careers that allow them to take time out of for child rearing without suffering too badly. For example, there are proportionally more female librarians than IT developers because taking time out from a career in a fast-developing field like IT can put a person's career back far more than a less fast-developing field such as librarianship. The fact that librarianship pays less well than IT, and attracts more men than women, is typical of the cause of the gender pay gap.