HP,

Thanks again for the information. I've saved everybody's answers to the quesstion and am trying to find how best to resolve the tension between win betting and exotics. All of the replies are helping.

Now onto another problem that I've been wrestling with. I would welcome a response from anyone.

Problem: establishing odds.
Premise: based on Thorograph numbers, I give every horse a rating of my own, again with lowest number being best. Now to turn these ratings into probabilities/odds?
Examples:

Horse__________a____b____c____d____e
Race 1 rating___4____6____7____12___20
Race 2 rating___4____10___11___15___20

Even though the spread between first and last is the same, horse a in race 1 should certainly be at somewhat higher odds than horse a in race 2, since he is closer to other contenders. How to get to odds from here, mathematically, without arbitrarily assigning odds to anyone.

Mike