Frequently Asked Questions
- What is the TrueNicks rating?
- Do nick ratings change over time?
- What is the variant score (the number displayed next to the nick rating) and how much weight should I give it?
- How far back do you go to assign a nick rating?
- What does No Rating mean?
- Does class (or any other factor) impact the TrueNicks rating?
- My question isn't covered here—where can I get more information?
The TrueNicks rating is a score that reflects the degree of affinity between the sire and broodmare sire (or sire line and broodmare sire line) of the subject horse or hypothetical mating. To ensure that the resultant rating is the result of true opportunity, the TrueNicks score is based on a calculation that examines all foals and all starters produced from the selected cross.
The TrueNicks rating is calculated by factoring two separate computations
- The Sire Improvement Index (SII), a comparison of the percentage of stakes winners that a sire (or sire line) has achieved with mares by the specific broodmare sire (or sire line), with the percentage of stakes winners that specific sire (or those specific members of the sire line) has achieved with all other mares
- The Broodmare Sire Improvement Index (BSII), a comparison of the percentage of stakes winners produced by daughters of a particular sire (or broodmare sire line) with the percentage of stakes winners from the same mares when bred to all other sires.
The resultant figure shows the stakes winner-to-starter production rate of the nick, compared to the stakes winner-to-starter production rate of the sire/sire line and broodmare sire/sire line when bred to representatives of all other lines. Thus, a TrueNicks score of 2.0 indicates that the cross has produced stakes winners at twice the rate that the sire/sire line and broodmare sire/sire line have when bred to all other lines. These ratings are translated into bands from A++ to F. (See also What is the variant score? below.)
Nick ratings are recalculated every day to take into account new foals, new starters, and new stakes winners. This ensures that breeders and buyers have the latest information available when considering their mating plans and purchases. Despite the continual updating of information, once a TrueNicks rating has been established, it generally takes several significant events for it to change rating bands.
The TrueNicks report includes the date and time of generation, printed in the upper right corner.
What is the variant score (the number displayed next to the nick rating) and how much weight should I give it?
The TrueNicks variant is a function of the Sire Improvement Index (SII) and Broodmare Sire Improvement Index (BSII).
The first step is to establish an SII, which is done by comparing the percentage of stakes winners to starters sired by a sire/sire line out of all mares by a broodmare sire/sire line, with the percentage of stakes winners sired by the same sire (or same representatives of the sire line) out of all other mares. An SII of 2.0 indicates the sire (or sire line) has twice the percentage of stakes winners out of mares by the broodmare sire/sire line as he does when bred to all other mares.
Next, the BSII is established by comparing the percentage of stakes winners to starters sired by a sire/sire line out of all mares by a broodmare sire/sire line, with the percentage of stakes winners produced by those mares when bred to all other stallions. A BSII of 3.0 indicates that that the percentage of stakes winners out of mares by the broodmare sire/sire line when bred to the chosen sire/sire line is 3.0 times as high as the percentage of stakes winners produced by that group of mares when bred to all other stallions.
The TrueNicks rating is calculated by multiplying the SII by the BSII. In the example above, an SII of 2.0 and a BSII of 3.0 would result in a TrueNicks score of 6.0, which translates to an A++ TrueNicks rating.
It is important to understand that the rating scale is not linear, so while a below-opportunity rating will have a variant of 0.01 to 0.99, an above-opportunity rating can have a score from 1.01 up to numbers as high as 500.00 and beyond. Generally, extremely high scores are the result of a mating which has had considerable success with limited opportunity. The best guide to the potential success of the nick is the letter rating which has been evolved through careful study of the relationship between the general population and the stakes winning population. Note that only 13% of the entire Thoroughbred population earn "A" ratings (A to A++) while 37% of stakes winners rate as "A's." Horses rated "B" or better (B to A++) represent just 30% of the entire population, yet three out of four (77%) stakes winners rate "B" or better. Almost half of Thoroughbreds in general — 44% — are on the low end of the scale (rated "C" through "F"), yet only two in 25 stakes winners (8%) have these lower ratings.
The TrueNicks program is designed to establish a rating within a minimum number of generations from the sire/broodmare sire cross. As soon as a cross has met statistically significant thresholds, a rating is calculated. The farthest the TrueNicks program will go to calculate a rating is to the third generation of the horse (or prospective mating) in the sire line, and the fourth generation of the horse (or prospective mating) in the broodmare sire line. Ratings beyond those parameters would be meaningless and will yield a No Rating score.
A classification of No Rating signifies that, after going back to the third generation in the sire line and the fourth generation in the broodmare sire line, the program has not found enough statistically significant evidence to calculate a rating.
Although there is insufficient information to calculate a valid TrueNicks rating, the TrueNicks report will list the best five horses bred on the selected cross, and occasionally one will find although there is insufficient data to calculate a rating, the immediate cross has indeed produced a stakes winner.
The TrueNicks rating is purely a reflection of the degree of affinity between the sire/sire line and broodmare sire/sire line. Thus, it is best used to differentiate between matings or individuals within a similar commercial range. This reflects the considerations that breeders and buyers are likely to face in “real world” situations. For example, it is more likely that a breeder considering using Giant's Causeway might also consider Distorted Humor or A.P. Indy – horses at a similar commercial level – rather than alternative stallions in the $20,000 range, and vice versa.
When planning or evaluating matings, other factors such as a balance of aptitudes (speed, stamina, preference for dirt, turf, or all-weather tracks), inbreeding, linebreeding and outcross, and conformation considerations must be kept in mind. TrueNicks is a tool to be used by the Thoroughbred breeder and owner and while studies of over 100,000 horse demonstrate that there is a high correlation between the affinity between the sire/sire line and broodmare sire/sire line that is information that cannot be ignored, it must be given the appropriate weight when considering all other factors that influence eventual racetrack performance.
SRO stands for Stallion Register Online, the online stallion database found at StallionRegister.com. When we mention a subscribed stallion in a blog post, a link to his SRO page appears after his name. Follow this link to get additional details about the stallion, such as conformation photos and progeny statistics.
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