I've been doing some research on Mine That Bird, the thoroughbred, and I have come across something that confuses me.

He won the Kentucky Derby at 50-1 odds in 2009. Giacomo also won at 50-1 in 2005. But Mine That Bird paid $103.20 for a $2 bet, whereas Giacomo paid $102.60. Why is there a difference in the payoff if they had the same odds? Does it have something to do with the way they calculate perimutuel betting, which I think is more complicated than they let on in the programs and the boards?

As someone who watches horseracing but doesn't generally gamble, some of the details of perimutuel betting are lost on me.

Thanks!

Were they the exact same bets? A win bet will pay more than a place bet.

I guess they round 50.6 (and 50.3) down to 50.

This link regarding Breakage should help and is along the lines of Tim's train of thought with percentages.

http://horseracing.about.com/library/blbreakage.htm

Yes, I was talking about $2 bets to win.

Ah! I thought it might be something like that. But where did you get those more precise figures on the horses' odds?

Thanks, I think that helps! But I'm still wondering you can get the more precise odds. Everything I've read says "50-1" for each horse.

http://www.derbytrail.com/forums/showthread.php?t=42219 (post 16) (or math)

This site quotes 50.6 - 1 for Mine That Bird

http://horseracing.about.com/od/kentuckyderby/tp/aalongshotderby.htm