Baseline Differential — The median of your last 20 round differentials. This represents your "true" level of play, resistant to outliers in either direction.

Recent Weighted Differential — A weighted average of your last 5 rounds, emphasizing the most recent: 35% · 25% · 20% · 12.5% · 7.5%. Captures current form more sensitively than a simple average.

Form Score — Baseline minus Recent Weighted. A positive score means you're playing better than your baseline (lower differentials are better in golf). A negative score means you're trending worse.

🔥 Hot — Form Score ≥ 1.5. Playing noticeably better than baseline over recent rounds.

😐 Neutral — Form Score between −1.5 and 1.5. Playing in line with their typical level.

🥶 Cold — Form Score ≤ −1.5. Recent rounds are meaningfully worse than baseline.

↑ Improving — Avg of last 3 rounds is at least 1.0 better than the prior 3.

→ Flat — Avg of last 3 rounds is within ±1.0 of the prior 3.

↓ Declining — Avg of last 3 rounds is at least 1.0 worse than the prior 3.

Standard deviation of the last 10 round differentials. Measures how consistent a golfer's scoring is round-to-round.

Low (<2.0) — Very consistent. Scores cluster tightly around their average.

Medium (2.0–4.0) — Normal variability for most amateur golfers.

High (>4.0) — Unpredictable. Big swings between good and bad rounds.

All differentials use GHIN's pre-calculated adjusted scaled-up differential, which correctly handles partial rounds (fewer than 18 holes played) per World Handicap System rules.

Calculated using the official World Handicap System formula:

Course HCP = HI × (Slope ÷ 113) + (CR − Par)

Where HI = Handicap Index, Slope = course slope rating, CR = course rating, and Par = course par. This gives each golfer's playing handicap for the specific tees being played.

Stroke Play — Full difference in course handicaps. Lower HCP gives strokes to higher HCP.

Match Play — ¾ of the full stroke difference per USGA guidelines, spread across the hardest holes on the scorecard.

Skins — Full stroke difference, allocated on the hardest holes (by stroke index).

Stableford — Each golfer plays off their full course handicap, earning points per hole relative to par.

Starts at 50/50 and adjusts based on four factors:

📐 Handicap strokes — ~3.5% edge per stroke received. A golfer getting 4 strokes starts with a ~14% base advantage.

🔥 Form Score — ~4% per point. A Hot golfer (score ≥1.5) can swing the probability by 6% or more.

📈 Trend — Improving = +3%, Declining = −3%. Captures momentum going into the round.

📊 Volatility — Low volatility = +2% (consistency is an edge), High volatility = −2% (unpredictable scoring).

Probability is capped at 5–95% — even a big mismatch leaves room for an upset. For entertainment purposes only.