[dabruinwarrior]

Hello,

I am a newbie at posting so I don't know if this is in the right place. I had a question. For both NCAA and NFL, I am playing at a local book that fixes their lines from wed/thurs, however the vig is 20%. Sometimes there is 4.5 to 6.5 pts gaps on both o/u's and pointspreads(difference from a current line to the fixed line). For example, last week on one line I had North Texas at +22.5. On another I had North Texas+17.5 I was looking at the push chart on another thread for both NCAA and NFL on both O/U and sports and I was confused on the frequency percentage because the bottom notes that the percentage is taken from a range of 2 or 3 pts. I was wondering if anyone out there knew when it is mathematically advantageous (what pt differential) to middle between a fixed line with 20% vig and moving (current line like pinnacle) with a vig of 5%.

Thank you.

[Ganchrow]

See this thread as well as the the half-point calculator.

[Dark Horse]

Picture is worth a thousand words. An example that, to me, was mathematically worth it. Perhaps others can also list middles that hit.

I had a projected total for the MNF game between NE and DEN of 47.5 pts. The total opened at 46 and moved to 48.5 before closing at 48. So the line moved across my projected number, and then back towards it.

The numbers 47 and 48 are among the six most frequent in the NFL; combining for roughly 8 percent of all final results.

I bet the middle and it won, reminding me that there is not a sweeter win in sports betting.

Was I lucky? Of course. You can't win a middle without luck.
But did it make sense? I'd like to think so.

The point? Factor in projections and line movement before going to push frequencies.

[tomcowley]

It really doesn't matter if you projected the total at 45, 47.5, or 50- that makes a minimal difference in the odds that it will land on 47-48 and therefore a minimal difference in the EV of the middle. If you played o46.5 -110, and the market is now 48.5 -110/-110 , then you DO have a +EV middle because you'll win about 7% of the time on a combination that pays 20:1. However, if you've bet o46.5 for a sane amount, and you consider the market to be fair at 48.5 -110/-110, you should just let o46.5 ride. It's higher EV and EG. You generally shouldn't middle a sane bet unless you think the second bet is 0EV or better on its own.

[Dark Horse]

I appreciate that in many cases a middle is a cancellation of a previously made bet. In other words, neutralizing a perceived edge.

In this case, I had no edge. I already knew that from the way I bet totals. The only bet that was interesting was the middle itself. So there was nothing to let ride.

Of course, it would be necessary to have those lines available simultaneously, and at good pricing.

[Dark Horse]

The problem with relying solely on push frequencies is that they don't include overlays. Anybody working closely with overlays knows that they can move in and out of hot zones. So you may be underestimating the importance of line movements.

[Data]

Originally Posted by tomcowley

However, if you've bet o46.5 for a sane amount, and you consider the market to be fair at 48.5 -110/-110, you should just let o46.5 ride. It's higher EV and EG.

Actually, middling, same as buying back with an arbitrage, is higher EG than holding initial position as it is. See this: Overbets and Line Changes -- A Kelly Spreadsheet

You generally shouldn't middle a sane bet unless you think the second bet is 0EV or better on its own.

While it is counterintuitive, if presented with arbitrage/middle opportunity, one should generally buy back. Even making -EV bets will achieve higher EU.

[tomcowley]

Restricting edges to whole numbers of cents, using -110 lines, and assuming the position you have is actually +EV vs. the line you're going to middle with, you should never middle a 1% bet with a line with more than 1c disadvantage (worse than -109 fair), and even on a 5% bet, you wouldn't buy any of it back with a -110 coinflip. So you basically never -EV middle a 1u bet, and never buy off even a 5u bet if you're just flipping on the second side.

And what on earth is an overlay in a hot zone?

[RickySteve]

Originally Posted by Dark Horse

The problem with relying solely on push frequencies is that they don't include overlays. Anybody working closely with overlays knows that they can move in and out of hot zones. So you may be underestimating the importance of line movements.

First ballot Post Hall of Fame.

[Casperwaits]

Yeah, after reading Dark Horse's reply I need to take a cold shower!!

[Data]

Originally Posted by tomcowley

never buy off even a 5u bet if you're just flipping on the second side.

According to Ganchrow's Line Change Calculator I referred to in my previous post, to maximize EU, you should buy back about 1.7u at -110.

[tomcowley]

What win% are you assigning the first 5% bet (at -110 odds) to suggest a 1.7% buyback on a -110 coinflip?

[Dark Horse]

-

[RickySteve]

Originally Posted by Dark Horse

-

An above-average post for you.

[Data]

Originally Posted by tomcowley

What win% are you assigning the first 5% bet (at -110 odds) to suggest a 1.7% buyback on a -110 coinflip?

I was looking at the scenario that you discussed with Dark Horse. Assigning 57% win probability to Over 46.5, a half-Kelly bettor will wager 4.85% at -110 with. Once the line moves to 48.5, he takes Under (buys back) 1.74% at -110. While this bet is -EV it maximizes bettor's EU.

[Dark Horse]

Originally Posted by RickySteve

An above-average post for you.

- -

[tomcowley]

Sure, if you bet big enough and have a low enough risk tolerance, you'll get a buyback. A bettor with a 5% position at 57% to win will not buy back anything at a -110 flip if trying to maximize EG.

[RickySteve]

Laugh out loud at my posts being deleted in this thread.

[donjuan]

The problem with relying solely on push frequencies is that they don't include overlays. Anybody working closely with overlays knows that they can move in and out of hot zones. So you may be underestimating the importance of line movements.

The thread said mathematically, not pseudo-scientifically.

[dwaechte]

Thanks data for bumping that thread with Ganch's spreadsheet and ensuing discussion, I'd been looking for that.

[Dark Horse]

Originally Posted by donjuan

The thread said mathematically, not pseudo-scientifically.

You wouldn't be the first self-absorbed math guy to put the cart before the horse.

It's as amusing as amazing to me that my earlier statement wouldn't be understood. Oh well..

Just for those who do get it. If you notice that your overlays move in and out of zones around actual 'football numbers', know that your line is very accurate. As well as mathematical.

[Data]

Originally Posted by tomcowley

Sure, if you bet big enough and have a low enough risk tolerance, you'll get a buyback.

A Kelly bettor should buy back no matter what his Kelly multiplier (risk tolerance) is. The buy back is going to be around 35% of his initial Kelly bet. If a Kelly bettor placed 5% bet that does not mean he overbet and was going to buy back. It means his Kelly multiplier is about 0.515.

A bettor with a 5% position at 57% to win will not buy back anything at a -110 flip if trying to maximize EG.

A Kelly bettor with a 5% position at 57% to win will buy back about 35% at a -110 flip if trying to maximize EU.

[Data]

Originally Posted by dwaechte

Thanks data for bumping that thread with Ganch's spreadsheet and ensuing discussion, I'd been looking for that.

I am glad you found something you were looking for, sir, especially considering what a great tool that spreadsheet is.

[tomcowley]

I'm not arguing what anybody would bet, unconstrained, in the first place. I said that somebody who HAS that position, due to limits, book balance, or any other factor (and presumably can't add more after a 2 pt line move), should let 5% ride to maximize EG.

I don't know how you're coming up with numbers that show anything else, unless you're just inventing a fictional kelly multiplier based on a previous bet and a currently estimated edge and assuming that the bettor would want to maximize that fraction of kelly for some unknown reason.

[tomcowley]

Originally Posted by Dark Horse

You wouldn't be the first self-absorbed math guy to put the cart before the horse.

It's as amusing as amazing to me that my earlier statement wouldn't be understood. Oh well..

Just for those who do get it. If you notice that your overlays move in and out of zones around actual 'football numbers', know that your line is very accurate. As well as mathematical.

Ok, I'll try again. What the hell is an overlay in a hot zone? Or, more simply, what is an overlay and what is a hot zone?

[Data]

Originally Posted by tomcowley

I'm not arguing what anybody would bet, unconstrained, in the first place. I said that somebody who HAS that position, due to limits, book balance, or any other factor (and presumably can't add more after a 2 pt line move), should let 5% ride to maximize EG.

In one of your previous posts 5% was a large bet (comparing to 1% bet). Now, it sounds like 5% was an underbet. If it was an underbet indeed then, of course, there is no reason to buy back.

One more thing, maximizing EG is wrong. I am guilty myself at saying a few times EG when I should have said EU.

I don't know how you're coming up with numbers that show anything else, unless you're just inventing a fictional kelly multiplier based on a previous bet and a currently estimated edge and assuming that the bettor would want to maximize that fraction of kelly for some unknown reason.

I assume that we are talking about Kelly bettors making Kelly bets. Those numbers coming right out of that assumption.

[tomcowley]

No, I was just saying that there's no reason to buy back even a 5% position @ 57% -110 (to maximize the full-kelly utility function) with a coinflip -110. All assumptions beyond that are yours. When it comes to middles, you generally have some position that you can't add more on to (and you may have even bet appropriately at the time, but further information caused the line to move and your edge to increase), or it's a halftime middle where even if you bet appropriately pregame, your edge has changed after the first half.

I agree that you would bet differently, assuming you could, with a 57% estimated edge, or with both lines simultaneously available. Most of the time, at least in my experience, you simply have some position, an estimate of your win%, and a line you can middle/arb with, and the problem is what to do in that situation, like right now with my combination of rays/phillies futures/series bets. If I could go back and adjust my initial positions to my current win%s, I'd make guaranteed millions this week, or bankrupt a lot of places, but I have to make do with what I have now, and it's the same after the line has moved or the game has gone to halftime.

[Dark Horse]

Originally Posted by tomcowley

Ok, I'll try again. What the hell is an overlay in a hot zone? Or, more simply, what is an overlay and what is a hot zone?

In this context an overlay is the point difference between your line and the line the bookmaker offers. As to hot zones or sweet spots, you can figure that out yourself. Provided your line is accurate, they, and not push frequencies, determine the real value of a line movement. Example: an over may be a stronger bet when the line is 40.5 than when the line is 40. It all starts with the accuracy of your line.

[Dark Horse]

Non-linearity. All over sports. Read up on chaos theory if you want scientific backing.

On a sidenote, do some of you math guys have any idea how arrogant you sound? Putting people down, asking questions as if anything you don't know must almost certainly be absurd. What's wrong with you? My two cents? Drop the act. Get real.

[Data]

Originally Posted by tomcowley

No, I was just saying that there's no reason to buy back even a 5% position @ 57% -110 (to maximize the full-kelly utility function) with a coinflip -110.

Originally Posted by tomcowley

However, if you've bet o46.5 for a sane amount, and you consider the market to be fair at 48.5 -110/-110, you should just let o46.5 ride. It's higher EV and EG.

So, "sane amount" means roughly a half of your ideal Kelly stake? This does not sound sane to me.

[donjuan]

On a sidenote, do some of you math guys have any idea how arrogant you sound? Putting people down, asking questions as if anything you don't know must almost certainly be absurd. What's wrong with you? My two cents? Drop the act. Get real.

You're obviously ignoring supernovas in saltwater lakes and their correlation to NHL 1st Period totals. That's the problem with assuming an efficient market and finding derivative bets that are off. Supernovas. Saltwater lakes. Super saltwater lakes. Hockey. 1st periods only. Superwater. Pseudoscience.

[Dark Horse]

[tomcowley]

Betting >5% on an NFL total is insane unless you're a top .1% (or maybe even better) handicapper. If you think your edge is bigger than that at the time you bet it, and it isn't because you beat a book to a huge information-based steam move (or find a horribly stale line, in which case there's no way I could even get 2% down on it, lucky to even get .5%, much less a full 5%), you're almost certainly wrong.

In this context an overlay is the point difference between your line and the line the bookmaker offers. As to hot zones or sweet spots, you can figure that out yourself. Provided your line is accurate, they, and not push frequencies, determine the real value of a line movement. Example: an over may be a stronger bet when the line is 40.5 than when the line is 40. It all starts with the accuracy of your line.

What? If I cap a total at 44, and the line does something, say, 39.5->40.5, I'm going to have more than a trivial difference in value than if I'd capped the total at 43 or 45? The difference in value, either way, is only from the times the game would land on 40, and if my numbers are perfectly accurate or just pulled out of a hat, the percentage chance of the game landing on 40 barely changes. The difference between o40.5 and o39.5 is very close regardless of whether the fair line for the total is 43 or 44.

What systematic reason is there for the over to hit more often when the WA line is o40.5 than when the WA line is o40?

[Dark Horse]

Never mind.

[Art Vandeleigh]

I had a middle possibilty going last Sunday in the Steelers-Giants game, if the Steelers won by 1 or 2 points I'd have cashed at more than 100-1 odds thanks to an anomaly at half time (with a halftime score of 9-7 Giants) at a betting exchange that's not Matchbook.

Things looked optimistic with about 8 minutes left and the Steelers leading 14-12 punting from their own 15 yard line. One defensive stop by the Steelers and maybe they could run out the clock or come close to it without needing to try and score, or back and forth identical scores from each team.

But as you may know, Steelers linebacker James Harrison was used as the back-up long snapper due to Center Greg Warren's injury and snapped the ball about 10 yards over the head of Mitch Berger the Steelers punter, out of the end zone for a safety.

I have never watched a middle sail over a punters head before, but you live and learn.

OK, back to your learned discussions good folks at Think Tank.