Calculating Edge - Loads of Moneylines

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  • Boner_18
    SBR Hall of Famer
    • 08-24-08
    • 8301

    #1
    Calculating Edge - Loads of Moneylines
    So I have been tracking my tennis handicapping (from my blog if interested) and am now interested in calculating my edge, or lack thereof. I know how to and have calculated implied probability from all the lines I bet. Unfortunately, I haven't tracked both sides of the lines I have been betting so will have to go back and get those numbers if I need to calculate vig-free implied probability.

    Now, I have all the percentages and actual outcomes but I don't know how to get to my edge from there because the lines are all over the board (about +300 to -300). Should I group them, is there some stats concept that will help me compare them all?

    I know this isn't correct but the average odds bet over 138 plays is 1.929 or -107.64 and I am winning at a 54% rate.

    Someone please hold my hand, point me in the right direct or help. Thanks.
  • Dunder
    Restricted User
    • 10-26-09
    • 3345

    #2
    A few things.

    1) A sample of 138 games is nowhere near enough.
    2) On the basis of the wide range of odds, if it were me, I would compare subsets or similar odds (-300 to -250, -250 to -200 etc), but again it needs bigger samples.

    Notwithstanding this your edge at present is as follows:

    54% ( your win rate)

    divided by

    1 divided by 1.929 = 51.84% (the average implied probability of the odds you have taken)

    = 1.0417

    minus 1

    i.e. 4.17%
    Comment
    • Justin7
      SBR Hall of Famer
      • 07-31-06
      • 8577

      #3
      I checked your spreadsheet... nothing there. It's a lot easier to analyze a player from the spreadsheet than a blog.

      That said, look at what Dunder said
      Comment
      • Boner_18
        SBR Hall of Famer
        • 08-24-08
        • 8301

        #4
        Ok great thanks. I suspected as much about the grouping. After I group them should I average them and compare my win probability as you did for each subset?

        What sort of number will be significant, both on the whole and for each grouping? At this rate I will have 552 plays this year, still probably to few right?
        Comment
        • Boner_18
          SBR Hall of Famer
          • 08-24-08
          • 8301

          #5
          And am I correct that vig-free implied probability is more accurate in comparing against my win rate for calculating my edge?
          Comment
          • Dunder
            Restricted User
            • 10-26-09
            • 3345

            #6
            Originally posted by Boner_18
            Ok great thanks. I suspected as much about the grouping. After I group them should I average them and compare my win probability as you did for each subset?

            What sort of number will be significant, both on the whole and for each grouping? At this rate I will have 552 plays this year, still probably to few right?
            Yes on both counts.
            In terms of what is a worthwhile sample size, aside from the obvious answer of the more, the better - I would begin to have trust in the data at around the 500 level.
            Comment
            • Dunder
              Restricted User
              • 10-26-09
              • 3345

              #7
              Originally posted by Boner_18
              And am I correct that vig-free implied probability is more accurate in comparing against my win rate for calculating my edge?
              No not really. If what you are calculating is your true edge (EV) then that should be done against the actual odds you bet at. Comparison against the no-vig line might be of interest but is a different thing.
              Comment
              • Boner_18
                SBR Hall of Famer
                • 08-24-08
                • 8301

                #8
                Awesome, thanks for the prompt and helpful responses.
                Comment
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