can someone help me understand what im missing in calculating +EV?

ok so im using a no vig fair odds calculator and an EV calculator to try and determine which side of a bet has better value but i must be missing something...

ill use tomorrow's seahawks/bears game as the example..

odds are currently -200 for seahawks and +165 for bears. this means the implied odds for the seahawks to win are 66.67% and 37.74% for the bears to win. when i take the vig out that makes the odds 63.86% for the seahawks and 36.14% for the bears. assuming i am placing a $100 bet, when i enter that into the EV calculator it gives me a value of -$4.21 for the seahawks and -$4.23 for the bears.

-4.21 is a bigger number than -4.23 so assuming i am doing this correctly (which i dont think i am), that would mean the seahawks are a better value even if not by much. now this is where i get confused: using that math, i would obviously get the same numbers for any bet where the favorite has -200 odds bc the underdog will always have +165 odds. 

so wat am i missing? thanks.

@jesty

 Just wanted to let you know I moved this to NFL Betting forum - you are more likely to get some answers in this section for what you're looking for. BOL! 

You are in a circular argument...

If you are using the odds to determine who has better EV, then comparing that EV to the odds you started with - you are always going to be in a circle. 

The part you are missing is either YOUR calculated chance of winning, OR the best market odds you can get.

So if you start with -200 and +165, that has to be a market average to mean anything.  If that is a market average of lets say 10 big sportsbooks - you can then use that tool to determine the actual midpoint.  That is all that calculator is doing for you - it is determining the midpoint in your range of odds - which is not actually the mathematical midpoint.  The farther you get away from a PK, the more the midpoint is going to skew towards the underdog.  In your case....  The true midpoint of -200 and +165 is -177/+177 (closer to the dog odds than the fav odds).

So now that you know the midpoint of this wager at an average of 10 books is -177, the question becomes can you get a wager on the fav at less than -177 or on the dog at better than +177.  That is when you have "+EV".  For instance, I can get the bears right now at +199.  According to your inputs of -200 and +165, this would be a "+EV" bet.

I hope I understood your question correctly but if not let me know.

BTW....

Just on an editorial note...

I take issue with using odds to determine EV.  

EV has to be determined by comparing your own number (your calculation of true results based probability) of chances to win vs widely available line.  The current line is not a predictor of results - it is a market that is set by money and masses.  It is not always efficient, and shouldnt be assumed to be so (otherwise you should never bet).

"EV has to be determined by comparing your own number (your calculation of true results based probability) of chances to win vs widely available line."

100 % agree.

Also as Van stated and to your original point important to restate it is not a given that -200 will equate to +165.  The further importance of having your own number and multiples lines to shop from.

loook i ll make it simple for you the only thing that counts in nfl games is what goes up om the board

if you have team home dog of 6.5 vs better team they are not good

also many teams west to east early suck raiders this year blow out wins in east

49 ers last two east games eliminated from play offs @ bills @ miami last week

then u have teams in east going west sucking eggs Saints +6 @ KC buried

+8 @ chargers wow 20-8 loss

Pats +11 @ 49ers i took yjem figured spread too much for 49ers lol 31 -13 loser

of course i always fade teams who beat no bodies like jet bears saints jags pats colts titans which happened to denver @ Chargers winning 24- 13 as a DOG then winds losing  4 wins in a row abd covers ATL. @ raiders Browns then rest then Colts

thats all that matter what goes up om board and who they beat

@tjones1270

What you've just said is one of the most insanely idiotic things I have ever heard. At no point in your rambling, incoherent response were you even close to anything that could be considered a rational thought. Everyone in this room is now dumber for having listened to it. I award you no points, and may God have mercy on your soul.

@tjones1270

NO west to KC? 
      If you’re going use this as an example you have to include GB to Minny,  Buff to Det., Pitt. to Cincy, etc

All pairs in same time zone, just like New Orleans & Kansas City

Billy Madison couldn't of said it better 

@vanzack

Riddle me this in earnest as I play exclusively alternate lines based on reasonably solid modeling. 

Am I justified in paying very little attention to +EV, and in my case closing line, since I'm setting my own spread.  That being said I am accepting their corresponding value.

@jesty

 Interesting thread thanks for the positive contribution.

lmao damn this was like beating a step child 

@unplucked_gem

For me, CLV is nothing more than a benchmark. A steady measure of a set place in time to compare my lines up against.  I use CL, not CLV. I don't try to get "CLV" like a lot do, because I try to beat the closing line by predicting results, not by where the line will move.

In your case, if you are using a results oriented model, then the most important thing you could do if you can predict CL is when to make your wagers. Furthermore, you should be measuring your derivative lines success against the main line success to make sure you are getting added value.

Since you can get main lines at 1 cent spreads at exchanges, and derivative lines are going to have bigger spreads than that, you are up against a bigger hurdle off the bat. But if you can overcome that, and get enough money down, then you are on to something.

I don't put much in to CLV other than a measure of your timing of your wagers, the more CLV the better your timing. But I am not convinced you can seek out CLV in order to win at sports gambling. For me, it is seeking out noise instead of signal.

@vanzack

 Many thanks.

@vanzack

 I love Billy Madison ??

@jesty

 You did the no vig part correct.  It is complicated because we do not know exactly where the sports books are placing the hold on each side, but you have a good estimate here.  A -200 favorite will not always have the other side be +165, that will depend on the hold of the Sportsbook.  The hold is determined by how confident the book is in their numbers. Both sides are -EV because the book is placing hold on both sides.  

if you are line shopping/steam chasing/top down betting you are looking for books that are offering better odds than the no vig line.  Same goes for modeling, but your EV will be based on your number and the best available price you can get.  So if I make the Seahawks -230 tonight and best I can get is -200, the difference is my EV.  It can be quite complicated and there isn’t a true science in calculating all this out, but you can get quite close theoretically.  

You also have to assume that the market is perfectly efficient which it isn’t which makes things more murky.  Add in variance now and you see that things are very murky when determining whether you have an edge or not.  The best way for beginners is a form of top down, with modeling being very difficult but where you can make the most money.  Let me know if I can clarify anything.