There's a way to get more statistical significance out of a smaller number of races...
A bettor who has an edge should be betting less on longshots than on favorites.* So, instead of looking at ROI for flat $2 bets, it makes more sense to look at ROI for proportional bets. And it turns out that the end result is much more statistically meaningful. (the standard deviation is much smaller when compared to the ROI fig.)
Here's a link to something I posted on another forum that gives an example of the difference:
http://sharpsportsbetting.com/forums....cgi/read/9760
If you or anyone posts a list of Desormeaux and Lezcano's races (showing odds and if they won), I'll calculate the proportional bet ROI and show how I did it.
--Dunbar
* Ed Thorp showed years ago that the optimal horseracing bet for bankroll growth is Edge*Bankroll/Odds. If you have a 10% edge and a $1000 bankroll, you should bet 10%*1000/2 = $50 on a 2-1 shot, but 10%*1000/10 = $10 on a 10-1 shot.
Some may argue that you do not have the same "edge" on every bet, and that you in fact have a bigger edge on longshots. But given how difficult it is to estimate our edge at all, it's probably safest to assume our edge is roughly the same on every bet.