Spread/ML Converter Needs Tweaking

[HedgeHog]

Spread/ML Converter needs an overhaul for the larger spreads. If you put 12 in as the SB line and put 100 for fav and dog prices, it displays a fair value money line of 766. One would expect the ML to be closer to 450.

The higher the line, the greater the degree of error it seems--giving a false buy signal on the favorite. I think Ganch addressed this same issue in respect to the 1/2 point calculator, in that it becomes less accurate the farther you go out.

[durito]

I was going to point this out also.

at 12 and more NCAABB you get over 100% chances of the favorite winning -- same thing with other sports at other numbers. i know its more difficult with less data at higher spreads, but something is off.

[Ganchrow]

As I wrote in a PM to another poster:

To be completely honest I have very little confidence in [the ML/Spread converter] at all. It's probably reasonably accurate for smallish spreads but as the spread increases the accuracy falls off pretty quickly.

The problem is that the utility implicitly assumes that a bijective correspondence exists between spreads and win probability when in reality that's simply not supported by either theory or data. For sufficiently small spreads, the difference between a SU win and a spread cover is little more than an issue of score distribution microstructure but as spread increases other factors becomes increasingly more important in determining the relationship.

The truth is that ... while the spread/ml converter ... might be an interesting toy for the sports betting dilettante it lacks sufficient predictive power to be of much use to the professional in all but the most trivial of cases.

[durito]

Thanks Ganch

[Justin7]

Any teaser player knows... the fair ML for a 10-pt favorite is about -420. In the Super Bowl, I'd guess it should be about -650 (not quite 760, but I lot higher than 420s that are available now).

A "tweak" I'd use for the ML converter: use a multiplier of (game total / 44), and apply that multiplier to the portion of the ML above or below 100... So a total of 55 and a ML of -200 would become (-100 - 100 *44/55), or about -180.

And for those sports investors paying attention, Patriots are CHEAP at -420.

[Wheell]

Historically the variance from the spread in a championship game (not just Super Bowls, but college as well) is higher than it is for a regular season game. -12 and -440 seems apt for this game.