Predictive strokes gained

Predictive strokes gained is the value of a shot you have not hit yet. It is worked out at shot level, before the swing, for the golfer standing over the ball: point at a target and it says what that target is worth, and the number moves as the target does.

Not the other meaning

The phrase is also used for something different: forecasting how a tour professional will perform in a tournament that has not been played, which is a tool for betting and fantasy golf. That work predicts a player over a week.

This is one golfer, one shot, one target, right now. Same two words, different job, and worth being clear about before anything else.

Why it is harder

After a shot, strokes gained is settled: you know where the ball finished, so it is subtraction. Before a shot you do not know, and you never will. Your shots land in a pattern, not on a point, so a target has to be priced across every place the ball might finish, weighted by how likely each one is.

That is why the number depends on you. Two golfers standing on the same yardage, aiming at the same flag, get different numbers, because one has a tighter pattern than the other.

A worked example

150 yards from the fairway, to a green 30 yards across, with the flag tucked 10 yards from the middle and rough beside it. A typical amateur at this distance scatters about 9.0 yards either side. Before a club is chosen, both targets can be priced:

The flag costs 0.020 strokes against the middle here, and it costs 19 percentage points of greens hit. Standing over the ball you are 2.945 strokes from holing out; the question is which target leaves you better off, and now it has a number instead of an opinion. Run it with your own spread.

It prices, you choose

A predictive number is a price on a choice. PinFlag prices every target you point at, with your own dispersion and the lie read from the course, and draws your real dispersion on the hole so you can see how much of it reaches the trouble. You add the wind on your neck, the lie under your ball and whether you need a birdie, and the decision is better for having both.