If it's statistics your using and you have the actual raw data, factor analysis might be more appropriate. It tells you the significance of the data points but in relation to each other. It will also tell you if those 8 you are looking at now are important to begin with, what their relevance is to each other and so on.

You then create a discriminant function or do some clustering to find out which group of factors, in which relative combination, most often represent winning horses.

You can then create a probability model that will help you determine when to wager on this group.

Or you could do like my wife does and pick the cute jockey and/or funny-named horse.

-Duck