[curious]

Suppose that you take an opening line at -13, then later in the day it is -11, then just before gametime it is -10.

Do you ever backup your original bet with another bet at the newline using the theory "If I liked it at -13, I like it even more at -10?".

And, if you do backup your original bet do you wait till just before gametime or as soon as you see the new and better line?

[diogee]

I usually back up my bets if the line moves a good amount in my favor after I search to see if I somehow missed an injury or if there is a player that was scratched from the line-up for some reason. After that I jump on it right away mainly in fear that the new line will get pounded and move the spread back against me.

[MadCapper]

never!

if you get it at -13 and it moves to -10 you are more often than not on the wrong side.

[durito]

Everything I do is based on line value. Everything is reevaluated after a line move. Ganch has several spreadsheets that can help you with this.

But, generally if you have -13 and the market moves to -10 you are going to win less often than you lose.

[curious]

Everything I do is based on line value. Everything is reevaluated after a line move. Ganch has several spreadsheets that can help you with this.

But, generally if you have -13 and the market moves to -10 you are going to win less often than you lose.

I think what you mean is that the line move itself is an indicator of line value? And, a move of this size indicates that there is not any value in this line? Did I understand that correctly?

[curious]

never!

if you get it at -13 and it moves to -10 you are more often than not on the wrong side.

Are you saying that line moves are a leading indicator?

[buztah]

never!

if you get it at -13 and it moves to -10 you are more often than not on the wrong side.

Same here in my experience.

[Justin7]

never!

if you get it at -13 and it moves to -10 you are more often than not on the wrong side.

Bingo!

[curious]

Bingo!

So, then you should bet on the other side?

[diogee]

never!

if you get it at -13 and it moves to -10 you are more often than not on the wrong side.

Agreed...usually due to player being held out of the game.

[Ganchrow]

So, then you should bet on the other side?

In your example, -13 likely represents a bad bet ... but it doesn't necessarily follow that +10 represents a good bet.

For an advantage bettor, the extent to which one should increase, decrease, or stick with one's current position after a line move (or after the appearance of any additional evidence) should be based on one's predetermined system of risk management (whatever that may be), making certain to alter posterior forecasts as necessary based on the new evidence.

[curious]

In your example, -13 likely represents a bad bet ... but it doesn't necessarily follow that +10 represents a good bet.

For an advantage bettor, the extent to which one should increase, decrease, or stick with one's current position after a line move (or after the appearance of any additional evidence) should be based on one's predetermined system of risk management (whatever that may be), making certain to alter posterior forecasts as necessary based on the new evidence.

According to the formula I am using -13 had an edge worthy of betting on. -11 then represented an even bigger edge. In my opinion, if I liked the edge at -13, I like it even more at -11. But, I don't take into account that the line move occurred, to me -11 is a new proposition.

It seems that what people are saying is that the fact that the line move occurred indicates that the -13 line was a "bad bet". I am wondering on what basis this conclusion is made.

[Ganchrow]

According to the formula I am using -13 had an edge worthy of betting on. -11 then represented an even bigger edge.

It seems that what people are saying is that the fact that the line move occurred indicates that the -13 line was a "bad bet". I am wondering on what basis this conclusion is made.

I'd personally tend to draw such a conclusion based on appeals to the principles of market efficiency and Bayesian inference. If a bettor believes that market efficiency carries any weight at all then from a Bayesian perspective he'll always need to reevaluate prior forecasts in light of the modified market consensus made apparent by a line change. Of course this still leaves open the question of the extent to which a given forecast should be sensitive to market conditions, but that's going to be based highly on the nature of the model itself.

In my opinion, if I liked the edge at -13, I like it even more at -11. But, I don't take into account that the line move occurred, to me -11 is a new proposition.

I hear you -- but even if you believe both both a forecast and its accuracy independent of the current market you still need to respect the correlation between the old and new bets. So even if you don't modify your probability forecasts after a line move (implying an increase in edge forecast) it would nevertheless be dangerous to consider it an entirely new proposition.

[acw]

you still need to respect the correlation between the old and new bets.

I do quite a bit of live betting. When betting with the Asian books no shortage of being able to get on enough (read I somehow use a bit of Kelly) Lets say I have an early bet on the Over/Under 2.5 on a proper football match and within 20 minutes there are 2 goals. Now good (I bet over) or bad (I bet under) I will continue to look at the match as if I never had a bet on it. Or do you have a nice formula/calculator that I should use?

And do you have an opinion on which books put up smarter prices than others?

[Munson15]

never!

if you get it at -13 and it moves to -10 you are more often than not on the wrong side.

I agree with you, and I certainly wouldn't be looking to add wood to that fire.

[thebigguy]

agreed.

[Data]

I'd personally tend to draw such a conclusion based on appeals to the principles of market efficiency and Bayesian inference. If a bettor believes that market efficiency carries any weight at all...

I am in this because I think that sportsbetting markets are inefficient and therefore profitable strategies exist. If a bettor believes that the market is efficient then his plays are limited to scalping and middling.

[Ganchrow]

I am in this because I think that sportsbetting markets are inefficient and therefore profitable strategies exist. If a bettor believes that the market is efficient then his plays are limited to scalping and middling.

Market efficiency need not be an absolute -- it's the process through which all markets are made increasingly accurate through the processing of new information.

[Justin7]

Paraphrasing Ganch below... If the market says you're full of shit, you usually are. If the free market says -10 is the right number and you bet -13, you're a chump. Realize, the reason this number moved to -10 is because the winning players (computer groups and those with better injury info) moved it there.

I'd never take the opposite side of a game I liked just because of the market price (unless I could take +12 after the move to -11). Assume you're a good 54% capper, and the guys moving the market are also at 54%. when you disagree, the collective is at 50%. Pass on those, and your win rate goes higher than 54%.

I'd personally tend to draw such a conclusion based on appeals to the principles of market efficiency and Bayesian inference. If a bettor believes that market efficiency carries any weight at all then from a Bayesian perspective he'll always need to reevaluate prior forecasts in light of the modified market consensus made apparent by a line change. Of course this still leaves open the question of the extent to which a given forecast should be sensitive to market conditions, but that's going to be based highly on the nature of the model itself.

I hear you -- but even if you believe both both a forecast and its accuracy independent of the current market you still need to respect the correlation between the old and new bets. So even if you don't modify your probability forecasts after a line move (implying an increase in edge forecast) it would nevertheless be dangerous to consider it an entirely new proposition.

[Data]

Market efficiency need not be an absolute -- it's the process through which all markets are made increasingly accurate through the processing of new information.

It seems that you are saying that the current line accounts for all available information and the line moves are due to appearance of new information. I say that the lines are frequently off and they may or may not move and that there are market agents who can process available information better than others, linesmakers included, have an opinion on what the line should be and pound the existing lines whenever they feel like doing it.

[Ganchrow]

It seems that you are saying that the current line accounts for all available information and the line moves are due to appearance of new information. I say that the lines are frequently off and they may or may not move and that there are market agents who can process available information better than others, linesmakers included, have an opinion on what the line should be and pound the existing lines whenever they feel like doing it.

Markets are powerful entities, allowing for the dynamic where the market as a whole (and that's any competitive market) is much smarter than any single agent. The point isn't that markets can't be beaten -- they can -- but rather that they need to be respected. Markets bring very valuable information to the table, which a market operator will ignore at his own peril.

[dogman]

Always respect line moves