Sunday, December 14, 2008
Two Steps Forward...One Step Back
It's also frustrating to take a step backwards in any project, but sometimes it's necessary. I noticed that the correlations in my earnings per start data were lower for 1999 to 2000 than the earlier year, and suspected that there was something funny going on in the data. It appears I was right. Because the data was collected sometime around late 2002 or 2003, the year 2000 crop had only a very limited number of starts in the data, and this likely resulted in more random variation and less correlation to previous years. Because the average correlations I've been reporting include this crop, I'm going to go back and recalculate them without it. What I know is going to happen is that the averages will all go up. What I don't know is whether there was any systematic bias in the results. By having one crop where the horses' four year old and up seasons weren't included, were sires whose offspring mature late being 'punished'? Would this have had any impact on the analysis I've been doing? Probably not, but there's certainly enough question that I'll eliminate the year 2000 crop so that the data represents something closer to a complete record of the performance of the included offspring.
Posted by Alex at Sunday, December 14, 2008