[gfree]

I have historical MLB closing lines from various sportsbooks. The lines I have only contain the moneyline of the favorite. What would be the most accurate way of converting these to the true probability? Should I just assume true dimelines?

[FreeFall]

Do they mention which book it's from?

[gfree]

The lines and from donbest and are from a number of books (CRIS, pinnacle, greek, matchbook, etc.)

[LT Profits]

That's a problem as those books have different linesets.

[LT Profits]

Oh wait, if you mean you have lines from EACH of those books for each game, then Pinny is 8 cents and CRIS and Greek are 20 cents. Ignore Matchbook.

[gfree]

Thanks. So for pinnacle, I would find the theoretical hold of a -104/-104 set of lines as 1.92%. Then just subtract 0.96% from each implied probability that I got from the moneyline favorites?

Also, do you know if the hold has stayed consistent through the years? Has pinnacle always had an 8 cent MLB line?

[MonkeyF0cker]

No, gfree. See this post from Ganch: An introduction to betting lines and percentages

You'll need to do this individually for each line as the hold is different for each line with the same vig (in terms of cents). The hold for a -120 favorite on an 8 cent line is only 1.69%. You also wouldn't simply subtract it from the implied probabilities anyway as the hold becomes heavy on the side of the favorite with longer odds.

[MonkeyF0cker]

You'll also need to note the breakoff points for each book of when the vig (in cents) is increased.