For an excellent and incisive account of the factors which worked together to turn the divorce bill into a piece of legislation with significant ramifications for The Woman Question, see Mary Poovey, “Covered but Not Bound: Caroline Norton and the 1857 Matrimonial Causes Act” in Uneven Developments . See also Lawrence Stone, Road to Divorce ; Lee Holcombe, Wives and Property ; Mary Lyndon Shanley, Feminism, Marriage and the Law in Victorian England ; and Dorothy Stetson, A Woman’s Issue: The Politics of Family Law Reform in England .
The underlying idea is simple but powerful. If we are trying to explain some phenomenon, X, then we need to identify variations in the likelihood of X or the rate of X, and look for potential causes that (1) vary across the relevant circumstances in a way that could explain X and (2) that we can connect to the outcomes for X in some way. For example, with the gender distinctive clothing question, some ways to better specify the question and look at it through comparisons are: