Arbusers

Hello everyone,

I am looking to get more serious in the sports betting world and I want to discuss some theory and some maths with you about middle betting.

I am still what you would consider a beginner in the betting world but I have a good understanding of gambling and odds in general as I played poker professionally for almost 2 years.

For the purpose of this example I will use a signal given by Oddstorm free service for middle alerts.

Game: Arsenal - Liverpool in Premier League

Under 4.5 @Bet365 for 1.175
Over 3.5 @Williamhill for 3

71.86% of our risk must go to the Bet365 28.14% of our risk must go to Williamhill

So basically if the event Amount of goals = [3 or less and 5 of more] happens, we lose 15.57% of our total bet
if the event Amount of goals = [4 goals] happens, we win 68.86% of our total bet

Now in order to calculate our expected value in this middle, we need to evaluate what % of the time this game will finish with 4 goals.

To do that I will use the odds given by Bet365 on Exact number of goals: 4 for this game.

Exact Total goals [4]: 5.00 @ Bet365 which means that Bet365 thinks that this game will finish with 4 goals about 20% of the time (actually it's less but just for the sake of the example we'll use this fugure).

So basically 80% of the time we lose 15.57% of our bet and 20% of the time we win 68.86% of our bet.

Expected value of this middle: 15.57% x 80% + 68.86% x 20% = 1.32%

So this middle has a 1.32% expected value over the long run. Am I correct?

What method could we use to get a sharper idea of the % of the time that the event: [4 goals] will occur?

Here is a screenshot of my excel calculation:



If I made any mistake in my reasoning or calculation, feel free to participate. Also, what are good middle alert service providers you could recommend?

A middle is when you have an arb with the possibility to win both bets in a special event. This is no middle, you lose money most of the time, and even if 1.32% would be true, i think that is too low, such high variance in these kind of bets that i would not take less than 4%.

I don't mean to be rude but you obviously did not understand my topic... This is indeed a middle (You win both bets if game ends with exactly 4 goals).

Now about the 1.32%, I used this game just for the sake of argument (we are not discussing wether or not it is enough, we are simply looking to place an EV+ bet which is the case here).

Now you talk about variance, I believe it is mostly determined by the % of the time where your middle will happen which is evaluated in this case to be 20%

Over 3,5 @ 3,00
Under 4,5 1,175

This is not a middle opportunity. Arbing 3,00 and 1,175 odds is a suicide.

I would consider it as a "middle opportunity" if odds were like this,

Over 3,5 @ 3,00
Under 4,25 @ 1,48

Agreed this is not a middle OPPORTUNITY. But it is a middle nonetheless.

The purpose of my topic was more to discuss the mathematical approach to betting middles in general, as I said, this particular example was just taken arbitrally amongst other and is not to be considered investment material.

So basically, I guess my question is, are my maths good here? I use 3 variables to determinate the expected value of a middle opportunity (Both odds and the probability that the middle event will occur)

Another question is, how can we determinate the probability of the middle event actually occuring more accuratly? In this case I used the odds from bet365 but how can we calculate the "true" probability?

To come up yourself with this kind of data you would have to study these markets in depth, and if you are able to do that, you might as well pick only the side with most value, no reason to venture into weird "middle" systems like that.

I don't see how it is weird, it's a simple middle bet... your judgement seems to be biased by the outcome of this particular example so I will help you and give you another one.

Over 2.5 @ Bookmaker A: 1.85
Under 3.5 @ Bookmaker B: 2.25

Estimation of event [3 goals] occuring: 20%

80% of the time either Bookmaker A or B will win and 20% of the time when event [3 goals] happens we will win both.



We have 80% chance of winning 1.52% and 20% chance of winning 103.05%. This middle bet therefore has a 21.83% expected value

if you take your exemple :
*********
So basically if the event Amount of goals = [3 or less and 5 of more] happens, we lose 15.57% of our total bet
if the event Amount of goals = [4 goals] happens, we win 68.86% of our total bet
************
so it means 68,86/15,57 = 4,42,

which is lower than bet directly 4 goals on bet365 at 5,

so it is not interesting this middle.