tag:blogger.com,1999:blog-38600807.post3189479915218360550..comments2008-06-25T13:06:31.118-04:00Brian Burkenoreply@blogger.comBlogger4125tag:blogger.com,1999:blog-38600807.post-52934021664768999472008-06-25T13:06:00.000-04:002008-06-25T13:06:00.000-04:00Tim-<BR/>My language is quite sloppy. You're right HFA itself isn't stronger with two evenly matched opponents. HFA has the same strength of effect no matter the opponent. It becomes more decisive when teams are close in ability.<BR/><BR/>I did what you suggested and looked at margin of victory across all types of match-ups. It's *extremely* linear at about 2.5-3.0 points regardless of the match-up type.Brian Burkehttp://www.blogger.com/profile/12371470711365236987noreply@blogger.comtag:blogger.com,1999:blog-38600807.post-24629350296052936502008-06-25T00:16:00.000-04:002008-06-25T00:16:00.000-04:00My question is what do you mean "home field advantage is more important for evenly matched teams"?<BR/><BR/>As the first comment discussed (and as you pointed out yourself to some extent) this curves is a natural consequence of a 2-3 point home field advantage (HFA). For a game with unevenly matched teams, then 2-3 points is not important and the better team will almost always win whether at home or away. But in a game with a evenly matched teams, then getting a few extra points for the home team will be quite valuable.<BR/><BR/>So I would ask if the 2-3 point HFA is as consistent in for games between evenly matched teams as it is for teams that are poorly matched. Rather than looking at (Winning %) vs (season win total diff), look at (margin of victory) vs (something like the "Simple Rating System" predictions). Then you can see if team get more than a 2-3 point bonus in close games and less than a 2-3 point bonus in lopsided games.Timhttp://www.blogger.com/profile/16344465776414455477noreply@blogger.comtag:blogger.com,1999:blog-38600807.post-73141433086231001702008-06-25T00:11:00.000-04:002008-06-25T00:11:00.000-04:00Got the spreadsheet. The equation fits the data extremely well. If I understand you, you're confirming that HFA is really the same for all games, but that it manifests itself as apparently more important the closer the opponents are in ability. <BR/><BR/>Or in other words, HFA stays constant, but we detect it more frequently the closer in ability the two opponents are.<BR/><BR/>Very well put. Not only that, you mathematically proved it! Brilliant.Brian Burkehttp://www.blogger.com/profile/12371470711365236987noreply@blogger.comtag:blogger.com,1999:blog-38600807.post-77864413140193161402008-06-24T23:52:00.000-04:002008-06-24T23:52:00.000-04:00Awesome!<BR/><BR/>This agrees very well with my theory that the HFA expressed as a win % between equally matched teams is constant and that the only reason it seems to decrease with differences among teams is a natural consequence of the logistic assumption.<BR/><BR/>Use the win difference % as a proxy for team rating (theoretical win % against an average opponent) and plug the team ratings into the logistic formula:<BR/><BR/>HFA*R1*(1-R2)/(HFA*R1*(1-R2)+(1-HFA)*R2*(1-R1))<BR/><BR/>for each team at home and average the result. What you get is a curved line that would fit your data very well! (I'm e-mailing you my spreadsheet to make this clearer.)Anonymousnoreply@blogger.com