No, it's just statistics. Sure, the reasons why people are leaving might be different, and their distribution of lifetimes might be the way they are because of

No, it's just statistics. Sure, the reasons why people are leaving might be different, and their distribution of lifetimes might be the way they are because of business reasons. But the math to determine that distribution will be the same. I actually went so far as to ask this question over at the Statistics stackexchange site. Being mathematicians, they debated it briefly, then concluded that it was possible to determine, which, to a mathematician, is the same thing as a solution. I'm still hoping somebody who's done the calculation will share the magic SQL query.