Very Different Nick Ratings For Same Mating

[Patuxet]

One system gives the mating an "A" the other gives it a "D+". What in the individual methodologies might account for such a variance? Does one system tend to give higher ratings?
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"He is pure air and fire and the dull elements of earth and water never appear in him; he is indeed a horse ..." Wm. Shakespeare - Henry V

[Shammy Davis]

Very good question, I've asked the same question myself. I'm particularly interested to know why in Truenicks A++, the variants can be in double digits.

[Tappiano]

Ask Byron he's on the site somewhere or over on facebook.

[brogers]

Patuxet,

The methodology is the same (i.e looking at sirelines to see their affinity for broodmare sirelines) but TrueNicks and eNicks have completely different calculations and thus will generate completely different scores.

TrueNicks uses the total known population of foals, runners and stakes winners tapping into the TJCIS Equineline database. Results from around the world are added to the TrueNicks calculation as soon as they hit the TJCIS database which in the case of North America races, is as soon as they are reported back to Equibase.

TrueNicks looks at three factors in determining the variant which then determines the Rating. We look at the percentage success of the cross at hand (stakes winners to runners), we then look at the success (Sw/Rns) of the sire/sireline with all other broodmare sirelines excepting the one at hand in the mating and we then look at the success (Sw/Rns) of the broodmare sire/sireline at hand with all other sires that it has been mated to. This generates two scores (a sire Index and a Broodmare Sire Index) which are then multiplied to create the variant.

eNicks does not use foals or runners to create its variant and score so they do not look at opportunity, at least in a realistic sense. They use the stakes population that they collect into their own database (what horses are in this database and when they are added is up to eNicks), they then create a hypothetical rating based on stakes populations only.

What eNicks does is look at the sire/sireline and see what percentage of the stakes winners population that this sire/sireline is and then compares this to the stakes winning percentage of the cross against the percentage of total stakes winners for the broodmare sire. As an example, Northern Dancer line stallions have sired 6.9% of the stakes winners produced out of Noholme mares, but Northern Dancer line stallions have sired 8% of all stakes winners, so Northern Dancer line stallions sire 14% less stakes winners when bred to Noholme line mares, so it is a C nick.

The other consideration is rules. There is a logic flow for the way that the calculation works its way through the pedigree (Sire with Broodmare sire, sire of sire and his sons with Broodmare Sire, etc) before it finds a relevant cross. I am not exactly sure how eNicks does their logic flow (they seem to have certain sires that they use as 'stoppers') but TrueNicks only goes as far as three generations on the sire and three through the broodmare sire. If there is not enough data then TrueNicks will return a No Rating as the mating hasn't been tried enough for a statistically valid assumption to me made. I know that eNicks goes a generation further back but when we looked at this with TrueNicks the calculation would often return with a meaningless recession to the norm (i.e they were all gathered around 1.00 variant or "C") and the number of horses that we were talking about needing this extra generation to create a rating was a very small part of the population as a whole so we elected not to go back that far.

So that is about the nuts and bolts as to why the two companies come up with different ratings. As far as your question "does on system tend to come up with higher ratings?", the answer is yes. Jason Hall at Thoroughbred Review did a independent comparative a year or so ago that he published.

http://www.thoroughbredreview.com/nickingcomparison.htm

Shammy,

The variant is nonlinear so it is not a proportional score. You can get some really high variant scores when the cross itself is very successful and the alternate matings for the sire and broodmare sire are not that good. It is rare but you do find it and we have seen some variants as high as 500 which means that it is operating 500x opportunity. That said, it doesnt mean that it is a 500x better mating which is why we put the Ratings in there. We are doing some work over this summer on variants which we hope to put out as a whitepaper or blog post but basically there is not a lot of difference between a variant of 2.00 and 500 in regards to its potential to become a stakes winner. I hope this helps.

Byron
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Byron Rogers
Performance Genetics
www.performancegenetics.com

[Patuxet]

Thank you, Byron, for your thorough and thoroughly understandable explanation. And thanks also for the link to Jason Hall's comparison study.

Interestingly of the two ratings I mentioned in my initial post in this thread TrueNicks came up with the "A". While that "A" rating was far from the determining factor -- biomechanical considerations and a shared affinity (both overt and crypto) for turf played a significant part -- I've twice repeated the mating to good effect, at least to the eye. And the mare goes back for a third try this season.

Allison
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"He is pure air and fire and the dull elements of earth and water never appear in him; he is indeed a horse ..." Wm. Shakespeare - Henry V