Chepstow draw bias

Yes, in places. Across 257 races from 2023-06-01 to 2026-06-09: over 9-12f — moderate: low (inside) favoured (iv 1.21). Check the A/E column before betting it: a bias the market already prices in is not an edge.

2023-06-01 – 2026-06-09 results · 257 races · updated 9 June 2026

5-6f · 106 races

No meaningful draw bias

5-6f · 106 races · field avg win 11.5%

No meaningful draw bias

Draw	Win %	Top-3 %	IV	A/E	PRB	Runs
Low (inside)	11.5% 39 wins	20.6%	1.00 vs course avg	1.02 vs market	61.3%	339
Middle	10.4% 29 wins	22.9%	0.90 vs course avg	0.63 vs market	62%	280
High (outside)	12.4% 38 wins	20.9%	1.08 vs course avg	1.29 vs market	60.5%	306

7-8f · 108 races

No meaningful draw bias

7-8f · 108 races · field avg win 10.3%

No meaningful draw bias

Draw	Win %	Top-3 %	IV	A/E	PRB	Runs
Low (inside)	10.9% 42 wins	18.5%	1.06 vs course avg	1.01 vs market	61.3%	384
Middle	9.8% 31 wins	18.4%	0.95 vs course avg	0.96 vs market	63.1%	316
High (outside)	10.1% 35 wins	16.4%	0.98 vs course avg	1.02 vs market	59%	348

9-12f · 43 races

Moderate: low (inside) favoured (IV 1.21)

9-12f · 43 races · field avg win 11%

Moderate: low (inside) favoured (IV 1.21)

Draw	Win %	Top-3 %	IV	A/E	PRB	Runs
Low (inside)	13.3% 19 wins	21%	1.21 vs course avg	1.07 vs market	60.4%	143
Middle	11.2% 13 wins	19.8%	1.02 vs course avg	1.03 vs market	62%	116
High (outside)	8.3% 11 wins	16.7%	0.76 vs course avg	0.87 vs market	56.2%	132

Common questions

Is there a draw bias at Chepstow?

Does the market already price in the Chepstow draw bias?

Not fully. The favoured thirds at Chepstow 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.

What do IV, A/E and PRB mean?

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.

Keep going

Method: stall numbers grouped into field thirds (low/middle/high) per race, so field size never skews the groups; IV against same-course same-band baseline; A/E against de-overrounded Betfair SP. Small samples are flagged rather than hidden. Racing Alpha does not accept bets. 18+ · BeGambleAware.org.