I drop the entire Will Pays matrix into a pre-formulated spreadsheet and typically use the top 3 favorites from the prior leg to compute the expected odds, so it\'s hard to say exactly, but the basic formula if you\'re just looking at the Will Pays for the winner in the prior leg is:
Leg2 $2 Win Price = 2x($2DD Price / Leg1 $2 Win Price) x ((1-Win Takeout)^2 / (1-DD Takeout))
and the Leg2 odds are just:
Odds Leg2 = (Leg2 $2 Win Price - 2)/2
The basic formula works OK much of the time, but it\'s prone to misleading results if the winner of the prior leg was a longshot or if the horse was not the same price in the doubles as in the win pool, an adverse effect that is amplified because of the fact you\'re only using one horse from the prior leg to compute the expected odds.