Question 1

Is there a draw bias at Yarmouth?

Accepted Answer

Yes, in places. Across 435 races from 2023-06-01 to 2026-06-09: over 5-6f — strong: low (inside) favoured (iv 1.37); over 9-12f — moderate: low (inside) favoured (iv 1.18). Check the A/E column before betting it: a bias the market already prices in is not an edge.

Question 2

Does the market already price in the Yarmouth draw bias?

Accepted Answer

Not fully. The favoured thirds at Yarmouth hold A/E at or above 1 in our window — the bias has not been completely priced away, which is where a draw edge can actually pay.

Question 3

What do IV, A/E and PRB mean?

Accepted Answer

IV (Impact Value) is the group's win rate versus all runners in the same races — 1.00 is neutral. A/E is actual wins versus what de-overrounded Betfair prices expected — below 1 means the market over-bets that group. PRB is the mean percentage of rivals beaten, a finer-grained placing measure.

Draw	Win %	Top-3 %	IV	A/E	PRB	Runs
Low (inside)	14.9% 73 wins	22.2%	1.37 vs course avg	1.22 vs market	66.1%	490
Middle	9.6% 38 wins	18.1%	0.88 vs course avg	0.86 vs market	61.3%	397
High (outside)	7.6% 34 wins	16.6%	0.70 vs course avg	0.84 vs market	59.8%	445

Draw	Win %	Top-3 %	IV	A/E	PRB	Runs
Low (inside)	10.8% 75 wins	19.1%	1.08 vs course avg	1.23 vs market	66.3%	695
Middle	10.1% 58 wins	17.5%	1.02 vs course avg	0.84 vs market	62.2%	572
High (outside)	8.9% 56 wins	14%	0.89 vs course avg	0.88 vs market	58.9%	628

Draw	Win %	Top-3 %	IV	A/E	PRB	Runs
Low (inside)	12.5% 43 wins	19%	1.18 vs course avg	1.38 vs market	67.4%	343
Middle	11.6% 33 wins	17.2%	1.09 vs course avg	1.02 vs market	62.1%	285
High (outside)	7.7% 24 wins	14.7%	0.72 vs course avg	0.57 vs market	59.8%	313

Yarmouth draw bias

5-6f · 146 races

7-8f · 189 races

9-12f · 100 races

Common questions

Is there a draw bias at Yarmouth?

Does the market already price in the Yarmouth draw bias?

What do IV, A/E and PRB mean?

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