You might think, given all the lateral moves in Big Law, that unceasing turnover is an unavoidable cost of doing business. After all, the business model of elite firms is built on attrition. The vast majority of firms don’t even quantify the cost of turnover.

Well, I have. I’ve collected and analyzed years of data involving lateral movement at numerous U.S. and international firms. The effort has been part of my research into best practices for attracting, retaining and promoting women leaders at elite firms.