Say you have a random variable X (e.g., kilometers driven). Getting its variance is straightforward. But what if you want to say, A percent of the variance in X is due to the Var(X) for female drivers and B percent is the rest, that is, Var(X) for male drivers? A + B should be 100 percent.
Is this possible? Are there assumptions to be made to simplify things? Independence of female and male drivers?