Correction, 1/3/12, 11:40 a.m. EST: The print edition of this story incorrectly stated that Gibson, Dunn & Crutcher had four women on its 15-partner executive committee in 2001. The firm had four women on this committee in 2011. The 15th paragraph of the story has been revised to reflect the correct information. We regret the error.

Our question was simple. After years of measuring women’s success in law firms primarily by the percentage of female equity partners, we wanted to use a more exacting standard. We wanted to know: How many women partners had advanced to the highest ranks of law firm hierarchies?