title: Validation of a regression model for standardizing lifetime racing performances of thoroughbreds.
abstract: OBJECTIVE
  To determine the relationship between prediction errors of a regression model of racing finish times and earnings or finish position; the relationship between standardized finish times, determined by use of this model, and earnings or finish position; and whether this model was valid when applied to data for horses that underwent surgical treatment.
  
  
  METHODS
  Survey.
  
  
  METHODS
  Records of 6,700 healthy Thoroughbreds racing in Louisiana and of 31 Thoroughbreds with idiopathic left laryngeal hemiplegia that underwent surgical treatment.
  
  
  METHODS
  Predicted and standardized finish times were calculated by use of the regression model for healthy horses, and the relationships between prediction error (actual--predicted finish time) and standardized finish times, and earnings and finish position, were examined. Then, the regression model was applied to data for horses with hemiplegia to determine whether the model was valid when used to calculate predicted and standardized finish times for lifetime performance data.
  
  
  RESULTS
  Prediction error and standardized finish times were negatively correlated with earnings and positively correlated with finish position and, thus, appeared to be reliable measures of racing performance. The regression model was found to be valid when applied to lifetime performance records of horses with laryngeal hemiplegia.
  
  
  CONCLUSIONS
  Prediction error and standardized finish times are measures of racing performance that can be used to compare performances among Thoroughbred racehorses across a variety of circumstances that would otherwise confound comparison.
authors.affiliation: Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge 70803, USA.
authors.forename: G S
authors.initials: GS
authors.lastname: Martin
authors.forename: E
authors.initials: E
authors.lastname: Strand
authors.forename: M T
authors.initials: MT
authors.lastname: Kearney
mesh_terms: D000818:Animals; D001947:Breeding; D006736:Horses / Q000502:physiology*; D010805:Physical Conditioning, Animal / Q000191:economics / Q000502:physiology*; D011996:Records / Q000662:veterinary; D012044:Regression Analysis; D012189:Retrospective Studies; D012420:Running / Q000191:economics / Q000502:physiology; D013177:Sports / Q000191:economics