Question for Justin re: HFA

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  • VegasVixen
    SBR Wise Guy
    • 09-03-10
    • 991

    #1
    Question for Justin re: HFA
    Hey guys, my questions reagrds applying home field advantage to my projected game score. For example, using NFL, if my #'s say away team 17, home team 21 I would then apply my HFA #, if it's 3 in this example I would add 3 to the home team score, making my projection 17-24. I'm pretty sure I read in Justin's book that he does -1.5 to away team, +1.5 to home team. Can someone help me understand why you should split it vs. just adding it to home team score?

    Thanks in advance!!

    ~VV~
  • Justin7
    SBR Hall of Famer
    • 07-31-06
    • 8577

    #2
    Originally posted by VegasVixen
    Hey guys, my questions reagrds applying home field advantage to my projected game score. For example, using NFL, if my #'s say away team 17, home team 21 I would then apply my HFA #, if it's 3 in this example I would add 3 to the home team score, making my projection 17-24. I'm pretty sure I read in Justin's book that he does -1.5 to away team, +1.5 to home team. Can someone help me understand why you should split it vs. just adding it to home team score?

    Thanks in advance!!

    ~VV~
    If you add 3 points to the home team, you just increased your total by 3 points (if you bet totals). If you split the HFA and apply +1.5 / -1.5, you don't screw up your totals.
    Comment
    • VegasVixen
      SBR Wise Guy
      • 09-03-10
      • 991

      #3
      Thanks Justin, makes perfect sense!
      Comment
      • TomG
        SBR Wise Guy
        • 10-29-07
        • 500

        #4
        this is awful.

        you can't just add/subtract points for hfa because not all points are equal.
        Comment
        • Justin7
          SBR Hall of Famer
          • 07-31-06
          • 8577

          #5
          Originally posted by TomG
          this is awful.

          you can't just add/subtract points for hfa because not all points are equal.
          There are better ways to do HFA. As far as simple approaches go, it's not bad.
          Comment
          • TomG
            SBR Wise Guy
            • 10-29-07
            • 500

            #6
            it is awful for football where the value of points is so important. consider the number of games lined around 3 and 7. just adding/subtracting 1.5 points to each team you risk crossing key numbers effectively treating the 3 as worth the same as the 2 and 4.
            Comment
            • Justin7
              SBR Hall of Famer
              • 07-31-06
              • 8577

              #7
              Originally posted by TomG
              it is awful for football where the value of points is so important. consider the number of games lined around 3 and 7. just adding/subtracting 1.5 points to each team you risk crossing key numbers effectively treating the 3 as worth the same as the 2 and 4.
              TomG,

              With the point add/subtract approach, the HFA affects the moneyline more on a percentage basis on games near Pick. As you said, this is because the fixed point move is likely to cross the "3". Home teams in NFL win almost 60% of their games.

              Do you think the HFA adds 10% to the win rate of all teams? Or is it more for close games, and less for blow-out games? A add/subtract does the latter.

              If you move a game from Pick to -3, the ML for that favorite isn't far from -150 (matching up with historical results of a 59% home win-rate). There are plenty of reasons why this approach to HFAs has problems, but I am not concerned about crossing the 3 or 7 as one of the problems.
              Comment
              • VegasVixen
                SBR Wise Guy
                • 09-03-10
                • 991

                #8
                Originally posted by TomG
                it is awful for football where the value of points is so important. consider the number of games lined around 3 and 7. just adding/subtracting 1.5 points to each team you risk crossing key numbers effectively treating the 3 as worth the same as the 2 and 4.
                When making my football line, after coming up with each team's total, I then "convert" it to a real football #. Per John Miller's book, only 13 #'s make up more than 2/3's of all final scores. 7-10-13-14-16-17-20-21-23-24-27-28-31. So, if my projected score is for example 16.5 to 22, using Justin's approach for HFA it becomes 15 - 23.5. Since it's very unlikely to score 15 in NFL, and impossible to score 23.5, my adjusted projection would be 16-23. Total is now 39 which is only .5 different from my original projection of 16.5 - 22...
                Comment
                • Justin7
                  SBR Hall of Famer
                  • 07-31-06
                  • 8577

                  #9
                  Originally posted by VegasVixen
                  When making my football line, after coming up with each team's total, I then "convert" it to a real football #. Per John Miller's book, only 13 #'s make up more than 2/3's of all final scores. 7-10-13-14-16-17-20-21-23-24-27-28-31. So, if my projected score is for example 16.5 to 22, using Justin's approach for HFA it becomes 15 - 23.5. Since it's very unlikely to score 15 in NFL, and impossible to score 23.5, my adjusted projection would be 16-23. Total is now 39 which is only .5 different from my original projection of 16.5 - 22...
                  I read Miller's work, and was not impressed.

                  In your example, you believe a team is a 5.5 point favorite, and the fair total is about 38.5. Why not use that raw score, instead of fudging it to -7/39?
                  Comment
                  • VegasVixen
                    SBR Wise Guy
                    • 09-03-10
                    • 991

                    #10
                    Originally posted by Justin7
                    I read Miller's work, and was not impressed.

                    In your example, you believe a team is a 5.5 point favorite, and the fair total is about 38.5. Why not use that raw score, instead of fudging it to -7/39?
                    It's 5.5 before HFA adjustment, which leads back to the original question. You would advocate apply the 1.5/-1.5 and use the new "raw" number and throw out Miller's recommendation of adjusting to more likely #'s?

                    Last season I just added the entire HFA to the home team. (Different amounts for different teams)...After backtesting & splitting it between the teams instead, I would have had 6 additional bets lost for the season (sides & totals)... not the direction I want to go thats why I made the original thread.

                    I really struggle with capping NFL compared to what I've done in baseball. With the MLB season winding down, I'm reading & researching everything I can to try to improve my football capping. I wouldn't say I was overly impressed with Miller's work either, but I'm trying to read/research everything I can. In addition to yours & Miller's books, I've also read Bobby Smith, Dan Gordon & Wong this summer to try to look at new approaches.

                    Thanks again for your time!

                    ~VV~
                    Comment
                    • illfuuptn
                      SBR MVP
                      • 03-17-10
                      • 1860

                      #11
                      In addition to what TomG said, wouldn't you also formulate HFA as a %? Obviously bumping a 1 point favorite up to 4 for HFA is drastically different from moving a 45 point favorite up to 48 and that's putting key numbers aside.
                      Comment
                      • skrtelfan
                        SBR MVP
                        • 10-09-08
                        • 1913

                        #12
                        Originally posted by Justin7
                        If you move a game from Pick to -3, the ML for that favorite isn't far from -150 (matching up with historical results of a 59% home win-rate). There are plenty of reasons why this approach to HFAs has problems, but I am not concerned about crossing the 3 or 7 as one of the problems.
                        What about moving from +1.5 to -1.5?
                        Comment
                        • Justin7
                          SBR Hall of Famer
                          • 07-31-06
                          • 8577

                          #13
                          Originally posted by illfuuptn
                          In addition to what TomG said, wouldn't you also formulate HFA as a %? Obviously bumping a 1 point favorite up to 4 for HFA is drastically different from moving a 45 point favorite up to 48 and that's putting key numbers aside.
                          Do you think a fixed % is the right way to treat HFA? Should you just determine the win probability, and add about 0.09 to it?

                          Does this mean that any favorite of more than -1000 (on a neutral field) is an auto-win?
                          Comment
                          • illfuuptn
                            SBR MVP
                            • 03-17-10
                            • 1860

                            #14
                            ^As a % of the neutral field spread. I'm not adding 9% to win probability, I'm maybe adding 20% of the neutral field spread to account for HFA.
                            Comment
                            • TomG
                              SBR Wise Guy
                              • 10-29-07
                              • 500

                              #15
                              Originally posted by Justin7
                              Do you think a fixed % is the right way to treat HFA? Should you just determine the win probability, and add about 0.09 to it?

                              Does this mean that any favorite of more than -1000 (on a neutral field) is an auto-win?
                              No one is suggesting this, Justin. The fact that other methods are bad doesn't imply simply adding/subtracting points to account for HFA is OK.
                              Comment
                              • Justin7
                                SBR Hall of Famer
                                • 07-31-06
                                • 8577

                                #16
                                Originally posted by TomG
                                No one is suggesting this, Justin. The fact that other methods are bad doesn't imply simply adding/subtracting points to account for HFA is OK.
                                How do you handle HFA?
                                Comment
                                • TomG
                                  SBR Wise Guy
                                  • 10-29-07
                                  • 500

                                  #17
                                  Originally posted by Justin7
                                  How do you handle HFA?
                                  The simplest way to account for HFA is to convert the spread into a ML. Then add a fixed number of cents. Then convert back to a spread.
                                  Comment
                                  • Justin7
                                    SBR Hall of Famer
                                    • 07-31-06
                                    • 8577

                                    #18
                                    Originally posted by TomG
                                    The simplest way to account for HFA is to convert the spread into a ML. Then add a fixed number of cents. Then convert back to a spread.
                                    So in NFL, if the home team should win about 59%, would you advocate adding 45-50 cents to all home favorites?

                                    what if it was a -1000 favorite? Would you adjust it to -1050?

                                    I'm not chop busting, just trying to understand your approach.
                                    Comment
                                    • CHUBNUT
                                      SBR Sharp
                                      • 06-30-09
                                      • 321

                                      #19
                                      I gave up trying years ago as it drove me mad and at the end of the day its whatever makes you happy. The reason I'm posting is that a while back I read an interesting article somewhere suggesting that the better the team, the less they have a HFA as their road performance is not such a drop off compared to bad teams. I'm open minded about it but might be worth considering.
                                      Comment
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