Labs · Trap bias

The inside trap is not the best trap.

Everyone knows trap 1 wins more. Across 594,152 british races it wins most at only 15 of the 55 track distances where the draw measurably matters.

594,152 races chi-squared, p < 0.001 show Australia run it yourself
55 of 86 track distances with a real biasthe rest are within chance
15 of 55 where trap 1 is bestthe other traps take the rest
49 of 55 where the outside is worstthe low end is consistent
6.1pp average gap, best to worst 16.7% is an even draw

What the data says

The outside can win

At Harlow 238m, trap 6 wins most — 20.5% across 14,781 races. That is the opposite of what the draw is supposed to do, and it happens at 11 distances.

The same track can flip

At Towcester, 260m favours trap 5, 270m favours trap 1, 460m favours trap 2, 480m favours trap 2, 500m favours trap 1, 712m favours trap 1.

Bias belongs to the track and the distance. Treating a course as having one bias loses most of the effect — and 8 tracks do this.

Losing is the predictable part

Which trap wins varies. Which trap loses barely does: the outside two are worst at 49 of the 55.

So the draw is a reliable handicap even where it is an unreliable advantage.

Every british track and distance

Winners only. A combination appears once it has 400 races; the ones marked real are those where a chi-squared test says a draw this uneven would turn up by chance less than once in a thousand times.

Traps 1 2 3 4 5 6
above an even draw below best trap
TrackDistanceRaces T1T2T3T4T5T6 GapVerdict
Shawfield 480m 5,832 20.3 19.2 19.2 21 19.4 0.9 20.1 real
Towcester 260m 1,291 16.1 16 17.1 16.3 18.6 15.3 18.4 real
Towcester 480m 4,704 17.1 18.7 16 16 15.1 14.3 17.5 real
Towcester 460m 423 19.6 21.7 18 15.6 16.1 9 12.7 real
Towcester 712m 515 22.3 18.8 21.4 15.1 10.3 12 12 real
Romford 225m 437 17.8 10.5 14.6 21.3 18.8 16.9 10.8 chance
Yarmouth 277m 941 15 15.4 22.8 19.4 12.8 14.6 10 real
Sheffield 480m 842 20.8 15.9 19.8 18.3 14.3 10.9 9.9 real
Belle Vue 590m 701 20.3 18.3 18.4 18.3 13.3 11.6 8.7 real
Henlow 550m 1,586 22.8 16.2 17.2 14.1 14.8 14.9 8.7 real
Nottingham 480m 1,702 19.7 16.3 20.6 16.2 12.4 14.9 8.2 real
Towcester 270m 7,186 20.1 17.7 18.9 19 12.4 11.9 8.2 real
Nottingham 680m 568 17.3 18.1 21 15.8 12.9 15 8.1 chance
Hove 500m 16,906 19.8 18.5 17.1 15.8 11.8 17 8 real
Hove 695m 1,257 20.1 18.6 16.8 16.1 12.3 16.1 7.8 real
Peterborough 250m 1,516 16.8 17.3 17.3 21.2 13.5 13.9 7.7 real
Sheffield 660m 1,453 20.9 19.1 16.3 13.2 15.3 15.1 7.7 real
Hove 490m 1,276 20.3 18.3 15.8 16 13.5 16.1 6.8 real
Harlow 238m 14,781 16.3 14.5 17.4 16.9 14.3 20.5 6.2 real
Peterborough 420m 417 17.3 17.7 16.8 18.7 12.5 17 6.2 chance
Swindon 262m 1,436 14.6 20.2 16.4 16.6 18.2 14 6.2 real
Towcester 500m 10,104 19.5 17.7 18.8 17.4 13.4 13.3 6.2 real
Henlow 277m 1,282 20.1 14.8 18.5 14 15.5 17 6.1 real
Oxford 450m 7,299 16.9 18.3 18.1 18.2 16.3 12.2 6.1 real
Towcester 655m 533 14.3 20.3 14.6 16.7 17.8 16.3 6 chance
Peterborough 620m 629 18.8 15.3 18.1 18.1 16.7 13 5.8 chance
Sunderland 261m 4,515 18.2 16.5 19.5 17.4 13.8 14.7 5.7 real
Newcastle 640m 1,228 19.3 17.7 15.3 16.4 13.7 17.7 5.6 chance
Hove 285m 6,716 19 16.4 15.9 15 14.1 19.6 5.5 real
Central Park 480m 11,391 17.3 15.6 17.6 15.7 14.2 19.6 5.4 real
Harlow 592m 811 18.2 17.8 18.9 14.1 13.6 17.5 5.3 chance
Sittingbourne 480m 3,793 17.5 17 16.8 16.6 13.4 18.7 5.3 real
Dunstall Park 270m 773 18.5 19.3 15.8 16.6 15.7 14.2 5.1 chance
Sheffield 280m 8,795 17 15.1 19.5 18.5 14.4 15.5 5.1 real
Sittingbourne 265m 412 16 14.8 19.7 15.8 14.6 19.2 5.1 chance
Newcastle 290m 1,702 15.6 16 18.1 19.7 14.7 15.9 5 chance
Oxford 253m 1,759 14.3 19.2 18 15.9 18.5 14.2 5 real
Star Pelaw 435m 1,574 18.7 16.8 18.2 18 14.6 13.7 5 chance
Sheffield 500m 30,595 18.5 17.3 18.2 16.8 13.6 15.6 4.9 real
Star Pelaw 245m 671 16.1 13.7 17.9 18.5 15.9 17.9 4.8 chance
Suffolk Downs 220m 459 14.6 19.4 17.4 16.6 15.7 16.3 4.8 chance
Valley 260m 3,058 14.6 16.8 16.6 15.3 17.3 19.4 4.8 real
Yarmouth 659m 724 18.8 16 18.9 17.5 14.2 14.5 4.7 chance
Dunstall Park 480m 1,695 18.4 17.5 17 16.9 16.3 13.8 4.6 chance
Nottingham 305m 2,185 15.9 16.6 18.3 19 14.4 15.8 4.6 chance
Yarmouth 462m 23,294 15.3 16.8 19 18.8 14.5 15.5 4.5 real
Central Park 491m 4,051 17.5 17.1 16.5 18.4 14.1 16.4 4.3 real
Kinsley 650m 558 15.9 17 16.3 19.7 15.6 15.4 4.3 chance
Newcastle 480m 36,450 16.6 16.1 18.9 17.7 14.6 16.1 4.3 real
Suffolk Downs 388m 4,400 17.3 17.8 17.9 15.9 13.6 17.5 4.3 real
Central Park 265m 6,878 17.6 16.4 18.3 16 14.1 17.5 4.2 real
Central Park 277m 4,400 15.6 16 17 16.4 15.4 19.6 4.2 real
Hove 515m 14,389 18.3 16.2 16.4 16.1 14.4 18.6 4.2 real
Peterborough 435m 9,931 17.1 17.7 18.4 18.1 14.2 14.4 4.2 real
Central Park 642m 641 15.9 18.3 17.5 17.5 16.7 14.2 4.1 chance
Mildenhall 375m 2,062 18.6 15.8 16.1 14.6 16.7 18.2 4 chance
Poole 450m 11,134 17.4 17.3 18.2 17.1 14.2 15.8 4 real
Harlow 415m 18,032 17.3 16.4 17.2 15.4 14.9 18.8 3.9 real
Kinsley 462m 22,780 16.5 16.3 18.9 17.7 15.7 15 3.9 real
Crayford 714m 1,208 15.4 14.6 17 16.9 18.4 17.8 3.8 chance
Henlow 460m 18,856 18.8 17.3 17.1 15.9 15 15.9 3.8 real
Swindon 480m 14,441 17 16.1 18.5 15.6 14.8 18 3.7 real
Pelaw Grange 435m 10,043 19 17.3 16.6 16.2 15.5 15.4 3.6 real
Perry Barr 480m 11,402 17.6 17.9 17.9 17.5 14.3 14.8 3.6 real
Doncaster 275m 6,051 15.9 15.3 16.8 18.6 15.6 17.8 3.3 real
Doncaster 450m 13,182 17.5 16.6 17.6 16.3 14.4 17.7 3.3 real
Doncaster 483m 8,068 16.3 16.5 17.9 15.5 15.3 18.6 3.3 real
Kinsley 268m 7,602 16.1 16.1 18 17.2 14.8 17.8 3.2 real
Sunderland 640m 868 15.1 18 16.5 18.3 16.5 15.7 3.2 chance
Wimbledon 480m 3,401 18.1 15.6 17.3 16.6 15.2 17.1 2.9 chance
Monmore 630m 4,640 16.6 18.6 16.2 15.8 16.5 16.2 2.8 chance
Romford 400m 42,087 18.1 17.2 16.8 16.3 15.4 16.2 2.7 real
Swindon 476m 14,073 17.1 18.3 16.8 16.5 15.7 15.6 2.7 real
Monmore 480m 35,615 17.5 16.7 17.9 16.1 15.3 16.5 2.6 real
Belle Vue 470m 14,399 16.8 16.2 18 17.8 15.8 15.5 2.5 real
Valley 460m 2,438 17.7 16.8 16.9 15.4 17.1 16.2 2.3 chance
Nottingham 500m 27,962 16.7 17.2 18 15.8 15.9 16.4 2.2 real
Romford 750m 473 15.6 16.1 15.9 17.3 17.3 17.8 2.2 chance
Crayford 380m 29,920 16.9 16.7 16.7 16.7 15.4 17.5 2.1 real
Oxford 650m 577 16.6 17.2 17.5 15.4 16.3 17 2.1 chance
Sunderland 450m 31,057 16.7 16.6 17.9 17.1 15.8 15.9 2.1 real
Hall Green 480m 8,503 17.3 17.2 17.1 16.3 15.4 16.6 1.9 chance
Monmore 264m 5,642 18.1 16.6 16.4 16.3 16.2 16.4 1.9 chance
Crayford 540m 7,626 16 16.6 16.6 16.8 16.2 17.8 1.8 chance
Perry Barr 275m 3,708 16.1 16.7 16.8 17.7 15.9 16.8 1.8 chance
Romford 575m 6,346 17.5 17.3 16.3 16.1 16.5 16.2 1.4 chance

31 of the 86 combinations came back within chance. They are listed too, marked chance — a test that only reports its positives is not a test.

Check it yourself

This page is the output of an open-source command-line tool. It downloads results through the API with your own key, caches them, and computes the table above. A free key reaches a rolling seven-day window — enough to watch it work; a live key reaches the archive.

git clone https://github.com/GreyhoundAPI/greyhound-racing-trap-bias
cd greyhound-racing-trap-bias
python -m gtb
An earlier version of this tool got the statistics wrong. It divided the gap between best and worst trap by the standard error of a single trap’s percentage, which overstates significance — badly on small samples, so the thinnest combinations rose to the top looking most convincing. Tested against generated races with no bias at all, it called 43% of them significant. The chi-squared test that replaced it calls none of them. Every number here comes from the corrected version, and the tool will tell you the same.

This is one free endpoint

The table above comes from results alone. Live Plus adds per-dog and per-trainer statistics — how a particular greyhound runs from a particular trap at a particular track, which is where a tendency becomes a prediction.

See Live Plus Get a free key