How Many Rounds Before Strokes-Gained Data Is Reliable?
TL;DROne round tells you nothing. Five rounds tells you direction. Ten rounds tells you truth.
Variance is enormous in amateur golf. One round of strokes-gained can show you "losing strokes to driving" when really you had two unlucky lies. Here's the sample size that makes the data actionable.
The reliability table
| Rounds tracked | What the data tells you | Confidence |
|---|---|---|
| 1 | Almost nothing | Low |
| 3 | Rough direction | Low |
| 5 | Your weakest category | Medium |
| 10 | Trends and gaps | Good |
| 20 | Stable averages | High |
| 50+ | Skill-level evidence | Very high |
Source:Mark Broadie, Every Shot Counts — sample-size analysis of strokes-gained variance; corroborated by Arccos round-level data.
What to do early
Don't make swing changes after 1 or 2 rounds of data. After 5, you can identify the weakest category with reasonable confidence. After 10, you can compare against handicap benchmarks and trust the result.
Stop guessing what to work on.
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