Fixed vs. True Parlay Odds (diverted)

Data · 12-03-07, 03:18 PM

Originally posted by Ganchrow

Good to see you around here, Data.

You need to play your 4-team -110 parlays elsewhere if you're only getting 10-1 (corresponding to a single-bet line set of -121.78).

At Bookmaker (for example), which pays out at true parlay odds, you'd receive +1,228.33 on 4-teamers.

Thank you, sir. It is good to be around such a fine individual as yourself.

Good catch with the odds, noticed that too. I think that was a glitch on TheGreek's side. They actually have the best parlays as they could be as the odds are multiplied, same as at Bookmaker/5Dimes. See for instance my other 4-teamers above with much higher odds.

Ganchrow · 12-03-07, 04:24 PM

Originally posted by Data

Good catch with the odds, noticed that too. I think that was a glitch on TheGreek's side. They actually have the best parlays as they could be as the odds are multiplied, same as at Bookmaker/5Dimes. See for instance my other 4-teamers above with much higher odds.

It's actually not a glitch. Oddly enough it's by design. Many books offer so-called "fixed parlays odds" when the underlying wagers are all listed at . This frequently corresponds to 13/5 on 2-teamers, 6/1 on 3-, and 10/1 on 4-. Of these, only the 6/1 is better than true parlays odds (which would be ~ ).

This results in a rather peculiar dynamic where a player would actually receive better odds when parlaying games at, for example, -110, -110, -110, and (true parlay odds of (1+¹⁰⁰/₁₁₀)³ × (1+¹⁰⁰/₁₂₀) ≈ ) than he would were he just to parlay 4 games all at -110.

The moral of the story is that when betting -110 parlays at books not offering true parlay odds (i.e., because playing these bets at another book would for whatever reason be infeasible), try to abide by the following:

never bet -110 parlays of more than 3-teams and generally try to avoid 2-team -110s as well (fixed odds 2-team parlays at +260 are only slightly worse than their true parlay odds counterparts at ~ -- that's the equivalent of a single-bet line set of ).
if you need to combine more than 3 bets into a single parlay try to include at least one game line different than -110. This will cause the entire parlay to be graded at fixed odds.
if you have no candidate bets at odds other than -110, but still want to combine more than 3 bets, consider picking a large money line favorite (hopefully at fairly low vig) on which you have no opinion and adding that to the parlay as a dummy bet. This may actually lower the vig you're paying. Example:

Let's say there are 4-games you want to parlay at -110 odds. Fixed odds on that would be , corresponding to vig of 1 - 50%⁴ × 11 = 31.25%.

Now consider what would happen to vig if you were to add to that parlay a -1600 ML bet on tonight's NE Pats game, which, based solely on The Greek's / market, we'd expect to win with probability 90.82% (for single-game vig of ~ 3.15%).

The new parlay would pay out at odds of (1+¹⁰⁰/₁₁₀)⁴ × (1+¹⁰⁰/₁₅₀₅) ≈ for vig of 1 - 50%⁴ × 90.82% × 14.1659 ≈ 19.59%.

So in other words, by including the large money line favorite in your parlay, you've manged to reduce vig from 32.50% to 19.59% (although you'll have reduced your win likelihood to 90.82% of what it had previously been).

Just to be clear, I'm not advocating always including a large money line favorite in all a player's parlays, but rather doing so only as a last resort at fixed parlay odds shops in order to force parlay odds from fixed to true.

(Anyway, Data, sorry to hijack your thread. If you want I can separate this out into its own thread.)

Data · 12-03-07, 07:09 PM

Originally posted by Ganchrow

It's actually not a glitch. Oddly enough it's by design. Many books offer so-called "fixed parlays odds" when the underlying wagers are all listed at . This frequently corresponds to 13/5 on 2-teamers, 6/1 on 3-, and 10/1 on 4-. Of these, only the 6/1 is better than true parlays odds (which would be ~ ).

This results in a rather peculiar dynamic where a player would actually receive better odds when parlaying games at, for example, -110, -110, -110, and (true parlay odds of (1+¹⁰⁰/₁₁₀)³ × (1+¹⁰⁰/₁₂₀) ≈ ) than he would were he just to parlay 4 games all at -110.

That is oddly indeed. I very much appreciate your comment as I was not aware of this. Please feel free to hijack my thread with whatever you feel is remotely relevant, I will be just thankful as I am now.

SBR_John · 12-04-07, 01:11 AM

-1505/+955 market, we'd expect to win with probability 90.82% (for single-game vig of ~ 3.15%).

The new parlay would pay out at odds of (1+¹⁰⁰/₁₁₀)⁴ × (1+¹⁰⁰/₁₅₀₅) ≈ 14.1659 for vig of 1 - 50%⁴ × 90.82% × 14.1659 ≈ 19.59%.

funny i was just going to say the same dog-gone thing.

Way to go Ganch!

idontlikerocks · 12-04-07, 01:22 AM

i believe we are seeing common sense put into formula