Originally posted on 06/06/2013:

I have to think about this more, but a quick answer:

Looking at it from a results standpoint, the way you're calculating it, profit / initial investment, suffices.

From a(n) predictive/analytical standpoint, profit / amount wagered is the more telling number. Some players make a ton of plays to grind out a 50% bankroll growth, while others pick a game a day and still grow 50%. The more plays needed to make profit, the lesser of an edge the player would have on his bets. If your goal is to have as big of an edge as possible, I'd rather make fewer bets to get to the same end point.