- David Thornton of OneBillionHands.com introduces the “Situation Score”—an empirical approach to measuring situational value in poker.
You just flopped straight-over-straight on a wet board against a maniac who has plenty of chips to lose. How good is it to be you?
Everyone knows this is a great situation. But we live in a post-Moneyball world; it’s time we knew exactly how great.
In the last decade, online poker has produced enough data to provide meaningful empirical answers. In this article we introduce a method for calculating a “Situation Score” and suggest two uses.
Calculating a Situation Score
The concept is straightforward: find players who have been in similar situations, and keep track of how much those players ended up winning (or losing) in the hand. Their average end-of-hand outcome is your Situation Score.
You can intuit why big data is required—there are many considerations in finding a similar situation: players’ positions, effective stacks, hole cards, prior actions, and images/tendencies; community cards, the pot. More data means more similar situations.
Here’s an example: you’re playing low limit heads up with 100 big blind effective stacks. For the past half hour, both you and your opponent have been playing snug. You’re dealt red Kings in the small blind, and your opponent is dealt red Aces.
This is a terrible situation for you. We queried a billion-hand database and found that players in your situation lose, on average, 57 big blinds. Thus, your Situation Score is -57 big blinds.
Using Situation Scores to Measure Luck and Performance
Measuring Luck
Imagine you flopped set-under-set after checking a small pair from the big blind. Your Situation Score before the flop was negligible—on average, small pairs don’t earn or lose a ton of chips. Your Situation Score after the flop is disastrous—on average, being on the wrong end of set-under-set costs most of your stack.
If you know your Situation Score immediately before and immediately after the flop, you can determine exactly how much the flop changed your expected end-of-hand outcome. (Call it your “Luck Score” for the flop.) This method also applies to the initial deal, the turn, and the river. It’s a simple but holistic way to capture precisely how much the cards helped or hurt.
Measuring Performance
Imagine your opponent shoves the river with the nut flush, and you gracefully lay down a medium flush. Your Situation Score before folding tells you how much players tend to lose in your shoes. After you fold, you know how much you actually lost.
By comparing your actual outcome to your Situation Score, you can finally ask and answer the right question: not how much money you lost, but how much better you performed than the average player in your shoes. In future articles, we’ll develop this notion into a Skill Score.
You can see Luck Scores in action in the “Luck Means More Than Bad Beats” post on OneBillionHands.com. For an example of a Skill Score, see “If Money Saved Is Money Earned, How Much Did Newhouse Earn?”
