ok I took a look at this and only looked at favs.

It showed a slight profit overall for laying to a set amount.

Straight Bet $100
Test Range 1: $453
Test Range 2: $-610
Test Range 3:$-2100

Bet to an Amount: $100 profit
Test Range 1: $-356.03
Test Range 2:$-331.10
Test Range 3:$-725

Lay Bet $100
Test Range 1:$-2066.50
Test Range 2: $-78
Test Range 3:$1022.00

Lay to Amount $100
Test Range 1: $-68.00
Test Range 2:$95.27
Test Range 3:$336.26

These periods covered the last 4 months of data in 10,000 horses per test range. (not all 10,000 made the criteria though).


Laying to a set amount is the only profitable method.