Hi all,

I have a sports betting theory question. I bet at low enough limits and lose enough money to be regularly offered various promotions and odds boosts at several online sites. I have a question about whether I am approaching these offers from a theoretically sound perspective or if I'm making sucker's bets when I think I'm being +EV.

The bulk of these offers are 2 or 3 leg parlays, i.e. something like Sharks +1.5/Avalanche -1.5 @ +275.

I attempt to determine which of these offers are worth betting on by:

1) ~30 or so minutes before the first leg of one of these boosted offers begins, I input the Pinnacle odds into this no-vig calculator to determine the no-vig probabilities of each leg hitting.

https://sportsbettingsites.org/betti...ig-calculator/

2) I use basic multiplication to calculate the combined probabilities of all legs hitting

3) I use the below Kelly Calculator to determine the appropriate bet size giving the probability of the parlay hitting and the size of my bankroll and the odds I am receiving

https://dqydj.com/kelly-criterion-bet-calculator/

Is this approach sound? It feels sound but I don't know enough math to be certain. Some of these parlay legs start several hours after the first leg begins, when I am calculate the odds off the pinnacle lines. Is this a significant risk, where I'm not actually calculating probabilities accurately? Are these kelly and/or no-vig calculators inaccurate? Are there other risks I'm not even cognizant of?

I am posting this because I have had a bad few weeks in a row where a lot of these bets have missed. I think this is because the sample size is small and when you make a lot of +150 to +750 bets, you're going to lose a lot of them --- but I'd like a sanity check.

My goal is to ensure I'm not making +EV bets when selectively betting these odds boosts, not throwing darts like the proverbial chimp.

Thank you for any comments!

If Pinnacle has the most accurate lines for the markets you are betting into, then step 1 is ok.

Assuming the events are independent of each other step 2 is ok.

After that, I'd be more worried that the book giving you these promotions is adjusting the parlay payout significantly in their favor, before worrying about whether the lines on the legs that don't start until several hours later might move against you.

Expected Value can be verified before you make the bet. Use the probability you calculated in step 2 to determine what the fair payout on a particular parlay should be. If the parlay payout quoted to you by the book before you confirm the bet is less than the fair payout, obviously you are making a bet with a negative expected value.

Thank you for the reply! A couple comments then 1 more question about approach:

This makes sense to me, and actually provides some reassurance about my approach. Logically it made sense to me but I'm new to this stuff so don't know if I am missing something obvious. I have been calculating the EV of all of these boosts using pinnacle no-vig odds to estimate "actual odds" -- it is very funny how many of these boosts are still terrible bets! I pass on 90% of these offers but still find 1 or 2 a day across the books I have access to, that are +EV per the above approach.

You do raise a good point about an odds boost that is say a two leg parlay with one leg starting at 3pm and another at 8pm -- maybe the bet is +EV looking at both no-vig pinnacle lines when I place the bet at 3pm, but the 8pm line could move against me to the extent that the bet is no longer +EV.

So that brings me to my other question:

say I find one of those wagers where the odds boost puts this into +EV territory when the first leg closes. There is risk that the later leg moves against me by the time that game begins -- is it a safe assumption to make that on balance, the pinnacle line is equally likely to move for me as it is against me during that gap between legs?

The main point I wanted to make is, try to confirm if the parlay payouts are fair to you, because I doubt they are. Obviously I can't say for sure without seeing what kind of odds boosts you are getting and what payouts are being quoted to you, but the book I work at reduces parlay payouts. You seem thoughtful enough that if you Google around you should be able to figure out how to calculate what the fair value of your payouts should be, and compare that to what payouts are being quoted to you to see if you are getting shorted.

As for line movements, that's a whole other topic that I wouldn't even worry about until you confirm if you are even getting a good deal on the payouts.