VALIDATION OF A REGRESSION-MODEL FOR STANDARDIZING LIFETIME

Objective--To determine the relationship between prediction errors of a regression model of racing finish times and earnings or finish posit ion; 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 surgica l treatment. Design--Survey. Sample Population--Records of 6,700 healt hy Thoroughbreds racing in Louisiana and of 31 Thoroughbreds with idio pathic left laryngeal hemiplegia that underwent surgical treatment. Pr ocedure--Predicted and standardized finish times were calculated by us e of the regression model for healthy horses, and the relationships be tween prediction error (actual - predicted finish time) and standardiz ed 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 predic ted and standardized finish times for lifetime performance data. Resul ts--Prediction error and standardized finish times were negatively cor related with earnings and positively correlated with finish position a nd, thus, appeared to be reliable measures of racing perfor mance. The regression model was found to be valid when applied to lifetime perfo rmance records of horses with laryngeal hemiplegia. Clinical Implicati ons--Prediction error and standardized finish times are measures of ra cing performance that can be used to compare performances among Thorou ghbred racehorses across a variety of circumstances that would otherwi se confound comparison.