If you are a female with ambitions of getting a promotion, then your chances of rising to the top halve if your superior is also a female. Researchers discovered that companies work hard to get one women into a senior position, but once this is achieved then the odds of another joining her halve. The study, published in Strategic Management Journal, analysed the top tiers of 1,500 firms from 1991 to 2011. The authors said “We thought that the hiring of one woman would lead to a snowball effect at a given company. In fact, what we find is exactly the opposite.” http://www.hrgrapevine.com/markets/hr/article/2015-04-10-female-promotion-chances-half-if-boss-is-also-female