The Environmental Effects of Pace of Race and Purse for 2-and 3-Year-Old Standardbred Trotters

E.A. Tolley; D.R. Notter; T.J. Marlowe.

Summary

The objectives of this study were (1) to depict performance records of Standardbred trotters, with specific emphasis on the effects of non-random assignment of horses to races within the class-of-race system in the U.S., and (2) to identify a bias occurring when one or more of the indicators of class, e.g., purse and pace, varies with an individual horse’s performance in that race. Data on 2- and 3-year-old Standardbred trotters entered in 1-mile (1.6 km) races at five tracks during the years 1975 through 1978 were obtained from the U.S. Trotting Association (USTA), Colombus, Ohio. Because of the class of race system, mean genetic differences in racing ability are expected to occur among horses chosen for inclusion in different races. Class of race appears to be a real and potentially significant source of variation. However, it is one that is poorly defined because it mixes genetic and environmental factors. The philosophy behind dividing horses by class of race suggests that differences in purse level and, presumably, in speed, may be associated with different classes. Therefore, we replaced class with two continuous variables, the within-horse effects of purse and pace, and included these separately and together as covariates in our statistical model. Purse and pace partially described the class of race. If pace (or purse) were totally environmental, the performance of a horse might be represented by a relatively simple linear model:

Racing time = sire effects₁ + horse effects₁ + pace + purse + other fixed effects + error₁

The interpretation of pace is complicated by the fact that the data reflect not only the performance of the horse but behavior of the racemates. When the horse is racing against faster racemates, it will have a faster time and vice versa. Thus, in order to depict that differences in pace also reflect differences in the average genetic merit of horses in the race, we need to have another equation and consider the two simultaneously. Some horses with the ability to race at higher speeds are given greater opportunities to win more prestigious races having higher purses than are their slower contemporaries. These differences in opportunity reflect not only differences between horses but also differences in sire progenies. Breeders and owners believe that these differences in winnings are indicative of underlying differences in genotype. Therefore, we may want to combine all information into an interdependent system of three equations.

System:

Eq. 1: Time = sire effects₁ + horse effects₁ + pace + purse + other fixed effects + error₁

Eq. 2: Pace = sire effects₂ + horse effects₂ + other fixed effects + error₂

Eq. 3: Purse = sire effects₃ + horse effects₃ + other fixed effects + error₃

This system of equations is consistent with descriptions of how breeders and owners seem to evaluate the racing ability of Standardbreds. We are primarily interested in the first equation in which time is the dependent variable. However, by adding a second or third equation to the system, we have defined pace or purse as a jointly dependent variable, i.e., a variable that can appear in the diagram as either a covariate or a dependent variable. The interpretation of pace or purse is complicated by the fact that the data reflect not only the performance of the horse but the decisions and behavior of the track officials, the driver, the owner, racemates, etc. To the extent to which pace, purse, or both are correlated with the error term in the primary equation (Eq.1), the estimators are biased and inconsistent. Potentially, the most popular and presumably genetically superior sires have some offspring competing at all purse and pace levels; however, offspring of lower quality sires would not likely compete for the most valuable purses nor would they race against very fast racemates. Thus, if we use ordinary least-squares methods, it is possible that parameter estimates of both covariates, as well as variance components, may be biased.

African Studies	Education	Media Studies
American Studies	History	Middle East and Islamic Studies
Ancient Near East and Egypt	Human Rights and Humanitarian Law	Musicology
Art History	International Law	Philosophy
Asian Studies	International Relations	Religious Studies
Biblical Studies	Jewish Studies	Slavic and Eurasian Studies
Biology	Languages and Linguistics	Social Sciences
Book History and Cartography	Life Sciences	Theology and World Christianity
Classical Studies	Literature and Cultural Studies

	All Time	Past 365 days	Past 30 Days
Abstract Views	34	34	3
Full Text Views	0	0	0
PDF Views & Downloads	0	0	0

The Environmental Effects of Pace of Race and Purse for 2-and 3-Year-Old Standardbred Trotters

Summary

Citation Info

Share link with colleague or librarian

State of Breeding Evaluation in Trotters

Metrics

Subjects

Authors

Open Access

Product Information

Company

Contact

The Environmental Effects of Pace of Race and Purse for 2-and 3-Year-Old Standardbred Trotters

Summary

Citation Info

Share link with colleague or librarian

State of Breeding Evaluation in Trotters

Table of Contents

Metrics

Metrics