Where to bet and where not to bet: a study into 2017 Starting Prices in British horseracing

February 11, 2018 Off By HBF Admin

The Horseracing Bettors Forum has undertaken a study into Starting Prices in Britain in 2017, measuring the “over-rounds” compared to what might be expected given a race’s field size.

“Over-rounds” are the bookmakers’ theoretical mark-ups and are derived from the sum of the amount that would need to be staked to return a fixed figure at each of the prevailing prices.

For instance, you would need to stake £20 at 4/1 to return £100 (your £80 winnings plus your £20 stake) but just £10 at 9/1. If you add up all of these stakes it indicates the amount which would need to be invested in proportion to the odds of all of the runners in a race to return £100 regardless of the outcome.

In nearly all instances, this figure will be larger than the £100 returned. You might need to stake £110 to guarantee a return of £100 come what may, or you might need to stake £120 to do the same, depending on how much the prices are in the bookmakers’ favour.

The difference between the amount staked and the amount returned – 10% or 20% perhaps – is the theoretical “over-round” which works in the bookmakers’ favour (though at this stage it must be acknowledged that a bookmaker is unlikely to lay every horse in strict proportion to that horse’s odds).

Over-round is affected by field-size, but not in a simple, linear, fashion. That is why a measure other than over-round-per-runner needs to be used.

HBF used an equation derived from a study into Starting Prices in 2014 by HBF member Simon Rowlands (https://www.timeform.com/horse-racing/features/rowley/Rowleyfile_Investigates_The_Industry_Starting_Price,_part_one) and then established the degree to which actual Starting Price over-rounds differed from that simple prediction.

The following are some of the findings.

  • Over-rounds were generally higher than those predicted by the 2014 model, suggesting that %s have crept up in real terms
  • The WORST courses for punters in terms of over-rounds compared to the model’s expectation are (in order): Ffos Las; Chelmsford City; and Towcester
  • The BEST courses for punters in terms of over-rounds are (in order): Nottingham; Catterick Bridge; and Thirsk
  • The smallest over-rounds (compared to the model) come in Chases, the biggest, perhaps unsurprisingly, in National Hunt Flat Races
  • Again, perhaps unsurprisingly (given that more is known of the horses and that odds can be set with greater confidence), handicaps have smaller over-rounds compared to non-handicaps

Summary tables can be found at the bottom of this piece, but it is worth just dwelling on the figures by individual course. In particular, the over-rounds at Ffos Las in 2017 were frequently out of kilter with what might be expected and merit investigation.

These include a card at Ffos Las on 25th August, 2017, when the following betting percentages were returned: 122% for a 6-runner handicap; 128% for an 8-runner handicap; 142% for a 10-runner non-handicap; 130% for a 7-runner handicap; 128% for a 7-runner handicap; 136% for a 7-runner handicap; and 131% for a 5-runner handicap, all of which figures greatly exceed what might usually be expected.

The returns for the card on 17th July, 2017, were not quite so eye-watering, but they included: 135% for a 13-runner handicap; 133% for a 12-runner handicap; and 132% for an 11-runner handicap.

Something odd is going on at the South-Wales course, with nearly all races disadvantageous to punters betting at Starting Prices compared to expectation, and sometimes by large amounts.

Ffos Las may be a course to steer clear of until an explanation – not to mention a solution – has been provided. 

 

Summary of methodology: races in which the same number of declared horses as runners were used to avoid skewing by late withdrawals; the average difference from “par” was taken for all qualifying races at a course; “par” was taken to be [100+(field size*((-0.0245*field size)+1.9286)]

Steve Tilley

Simon Rowlands

February 2018

In the below table, the figure given is the over round compared to par, with a positive value an excess (i.e. poorer value betting track than par) and a negative value a better value betting track than par.

Course Diff
FFOS LAS 6.4
CHELMSFORD 4.3
TOWCESTER 3.3
CARTMEL 3.1
BATH 2.4
LINGFIELD 2.4
EXETER 2.1
TAUNTON 2.1
NEWTON ABBOT 1.8
AINTREE 1.6
MARKET RASEN 1.6
YORK 1.5
CHESTER 1.4
PLUMPTON 1.4
SALISBURY 1.4
CHEPSTOW 1.3
EPSOM 1.3
BANGOR 1.2
BRIGHTON 1.2
FAKENHAM 1.1
FONTWELL 1.1
LUDLOW 1.1
UTTOXETER 1.1
GOODWOOD 1
ASCOT 0.9
STRATFORD 0.8
WINCANTON 0.8
PONTEFRACT 0.7
KEMPTON 0.6
DONCASTER 0.5
HAYDOCK 0.4
RIPON 0.4
BEVERLEY 0.3
CARLISLE 0.3
HEREFORD 0.3
AYR 0.2
HUNTINGDON 0.1
WINDSOR 0.1
WOLVERHAMPTON 0.1
HAMILTON 0
NEWCASTLE 0
SANDOWN 0
WARWICK 0
KELSO -0.1
LEICESTER -0.1
CHELTENHAM -0.2
HEXHAM -0.2
NEWMARKET -0.2
REDCAR -0.2
SEDGEFIELD -0.2
WORCESTER -0.2
WETHERBY -0.3
PERTH -0.4
YARMOUTH -0.4
SOUTHWELL -0.5
MUSSELBURGH -0.6
NEWBURY -0.6
THIRSK -0.7
CATTERICK -1
NOTTINGHAM -1.7