Calculation of WPR

TRB Comment: 

The WPRs shown against each horse's past run are reflective of a range of factors including the quality of race times and sectionals (refer WPR User Guide). The method GTX uses to assign a base rating is relatively simple (but still produces great results) and that's by intent. It allows users who might want to get into understanding horses, form etc. to extract more value out of the ratings by forecasting the likely performance of each horse based on their past ratings as well as the suitability of the race coming up, including the pace shape, horses position etc. This will generally deliver the best benefit from using the ratings.

You can use additional tools and insights to help you forecast rating performance in the upcoming race, by identifying potential improvers, horses that might not run as well because of changes in race shape, or other reasons. It's not entirely necessary though.

Question: How is the WPR Predictive Rating for today calculated?

TRB Response:   GTX uses a concept called a "Master Rating" for each horse. That rating is based on a horse's history of both actual performances and expected performance, derived from its starting price. 

For example, take a simple scenario where two first starters run a rating of 81 and one starts at $21 and the other at $2.50 

The next time they start, if they had the same weight, the horse that started at $2.50 would have a higher master rating than the one that started at $21 

The master rating is adjusted after each start depending on performance. 

It's built around a philosophy that a horse's form is dynamic and a horse is much more than it has displayed at its last 1-2-3 starts. 

Previous peak form and as mentioned, expected performances as indicated by its market price have historically shown to be important influencers. 

It does a good job across a large number of races, but that's not to say the method is faultless. It's purposely designed at a relatively basic level, to allow individual users to extract further value out of the rating via their own analysis and by making personal adjustments... which is a different topic in itself.

Question:  Can you please comment on inherent weaknesses that might exist in the WPR rating methodology?

TRB Response: There are no consistent scenarios that indicate weakness (to our knowledge).

 That doesn't mean the automated assessments could not be better, of course, they can... but It's very much a case of how an individual race presents. 

The goal is to try and forecast the level of performance you think the horse will reach in this race based on past form, suitability of conditions and the suitability of the upcoming race, considering form, distance, track condition, map, pace etc. 

Regression to the mean is an important concept. Be cautious of well-exposed horses that suddenly run a ‘spike’ rating. The form is dynamic throughout a horse’s career, made up of ratings in line with its median level of talent, some well above and others well below.  A horse is much more than how it performed the last start, so it's important to look at its overall form, stage of career cycle etc. and come up with a figure that makes sense to what you can expect today.  

Adopting the logic of "if it looks right, leave it" is perfect... that will save time and ensure you aren't tuning out some of the inherent value in the automated process. If it doesn't look right, then it's a matter of considering all of those things mentioned above and coming up with a figure.