Is the Betfair price really better ? ( horse racing )

[Datapunter]

From reading information at various websites and forums i understand that it is commanly accepted that the price at Betfair is 20% better that the bookmakers. One reason is the traditional bookmaker 10%-12% overround is reduced to 1%-2%, add to that fluctuation in price because thats how a financial market works, and a general rule of 20% better seams plausible. Now i'm looking into UK horse racing and i am wondering if the general rule of 20% better price than the bookmakers, and i am interpreting this as 20% better than SP, is also valid for UK horse racing ? Does anyone have any data to support this ? Or to make a case for a different situation ? I've been looking at some specific sections of the market like hot favourites, maidens, sprints, and i'm getting results that do not follow the 20% rule at all. So i'm wondering if these are execptions or if the 20% rule is not valid.

[dave]

Re: Is the Betfair price really better ? ( horse racing ) I've seen data (don't ask me where, haven't got a clue), and it seems that at shorter prices the price advantage is small (maybe only 1 or 2% at short odds-on prices), while a 50/1 horse could be 100% better on betfair.