TOBA Study
A few weeks ago the Thoroughbred Owners and Breeders Association (TOBA) released a study in advance of the much anticipated Equine Injury Database initial analysis conducted by Dr. Tim Parkin.
The TOBA study looks at the percentage of starters that never raced again after not finishing their last start (career ending did not finish or CEDNF). While not all horses that fall into this category may have actually suffered a career ending injury, there is no reason to think that the proportion of CEDNFs that resulted from injuries would be any different across surfaces so it is a reasonable measure on which to base a study.
Equibase President Hank Zeitlin stated “This data was organized by certain criteria without interpretation...This data set was provided to TOBA for its internal use and was not professionally evaluated for statistical significance.”
Fortunately, it doesn't take a professional to test whether CEDNFs are statistically different between dirt and all-weather surfaces. Any basic statistics course should cover tests of two population proportions.
The 95% confidence interval for a population proportion is pbar ± 1.96*sqrt((pbar*(1-pbar))/n) where pbar is %CEDNF and n is the number of starts.
The results show that there is a statistically significant difference between CEDNF for dirt and all-weather surfaces (see table below). This is in contrast to the findings on breakdowns from the Equine Injury Database (no signficant difference between surfaces).
Does this mean synthetic surfaces are safer? NO
None of these studies controls for enough variables that impact injury. The most notable bias results from the age difference between dirt and synthetic surfaces. The oldest all-weather surface in the U.S. is Turfway Park at 5 years old. When was the last time Saratoga or Pimlico was resurfaced? You can't compare a dirt track with a 30 year old base to a new synthetic surface. It may just be that if Turfway had rolled out a new dirt surface that fatalities would've been reduced even more. Furthermore there are variations in weather conditions, racing population, medications, and prerace vet checks that should be accounted for. Truxton had a horse that could not get cleared by the vet at Presque Isle but would've likely been able to race at almost any other track in the country.
At some point the Equine Injury database is going show a significant difference in breakdowns between dirt and all-weather surfaced. Don't believe for a second that this means that synthetic surfaces are safer. The results of these studies are meaningless and a waste of industry resources.
The TOBA study looks at the percentage of starters that never raced again after not finishing their last start (career ending did not finish or CEDNF). While not all horses that fall into this category may have actually suffered a career ending injury, there is no reason to think that the proportion of CEDNFs that resulted from injuries would be any different across surfaces so it is a reasonable measure on which to base a study.
Equibase President Hank Zeitlin stated “This data was organized by certain criteria without interpretation...This data set was provided to TOBA for its internal use and was not professionally evaluated for statistical significance.”
Fortunately, it doesn't take a professional to test whether CEDNFs are statistically different between dirt and all-weather surfaces. Any basic statistics course should cover tests of two population proportions.
The 95% confidence interval for a population proportion is pbar ± 1.96*sqrt((pbar*(1-pbar))/n) where pbar is %CEDNF and n is the number of starts.
The results show that there is a statistically significant difference between CEDNF for dirt and all-weather surfaces (see table below). This is in contrast to the findings on breakdowns from the Equine Injury Database (no signficant difference between surfaces).
Does this mean synthetic surfaces are safer? NO
None of these studies controls for enough variables that impact injury. The most notable bias results from the age difference between dirt and synthetic surfaces. The oldest all-weather surface in the U.S. is Turfway Park at 5 years old. When was the last time Saratoga or Pimlico was resurfaced? You can't compare a dirt track with a 30 year old base to a new synthetic surface. It may just be that if Turfway had rolled out a new dirt surface that fatalities would've been reduced even more. Furthermore there are variations in weather conditions, racing population, medications, and prerace vet checks that should be accounted for. Truxton had a horse that could not get cleared by the vet at Presque Isle but would've likely been able to race at almost any other track in the country.
At some point the Equine Injury database is going show a significant difference in breakdowns between dirt and all-weather surfaced. Don't believe for a second that this means that synthetic surfaces are safer. The results of these studies are meaningless and a waste of industry resources.
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