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Fwd: Re: 0.4 vs 0.48 (Hoopstudies)

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  • Dean Oliver
    Message 1 of 1 , Feb 16, 2002
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      >This came from "jamisont1"



      >From: "jamisont1" <jamisont1@...>
      >To: "HoopStudies" <deano@...>
      >Subject: Re: 0.4 vs 0.48 (Hoopstudies)
      >
      >
      > >>>>Basically, the estimate formula using 0.4 ends up an average of
      >about 2% too high (91 poss vs 89 poss actual).
      >
      >You are right Dean, +2 more possessions per game than actual
      >possessions if you use 0.4.
      >
      >I think John and Dean both are Correct on this one.
      >Using 0.48 is more right if you only consider the free throw
      >percentage only, and using 0.35 is more right if u consider total
      >possession per game.
      >
      >The actual percentage of technicals, bonus free throws, and 3point
      >fouls is a lil higher than 0.4 (im not sure how much higher but I
      >calculated alleyoops2's free thow data and it was 0.43%)
      >
      >but if you put 0.48 on this (Possessions=FGA-OR+TO+0.4*FTA),
      >possession error margin will be larger.
      >
      >Why eror margins is larger for using more accurate number?
      >cuz that formular has a big error on blocked shots.
      >
      >lets say.. you shoot a ball (shooting attempt) then get blocked, it
      >goes out of bounds or ur teammates picks it up. then you still keep
      >the ball.
      >
      >real possession is just 1 since there was no change of possession,
      >but its 2 possessions according to that formular, +1 error margin)
      >
      >I looked at NBA team's average block shots per game. it was 5.4 last
      >year.
      >When you get blocked, i think theres more than 50% chance your team
      >will get it back. (alot of block shots just go out of bounds)
      >
      >so there is more than +2.2 error on that formular per game
      >consistantly.
      >thats why using 0.35 or 0.32 is more accurate than using 0.48
      >
      >Am i right on this? I hope i do....
      >damn its 4 am.
      >
      >
      >--- In APBR_analysis@y..., "HoopStudies" <deano@r...> wrote:
      > > --- In APBR_analysis@y..., "HoopStudies" <deano@r...> wrote:
      > > > I'm also seeing that more flagrant fouls and more technicals due
      >to
      > > > the new defensive 3-s rule might actually be lowering the 0.4. I
      > > did
      > > > the Det-NJN game, the Den-Mem game, and the Sac-Was game from
      > > > yesterday. In all cases multipliers of 0.32-0.35 work best. My
      > > > original work back in the mid '80's started with a multiplier of
      > > > 0.36, I remember. But that was based on the 1987 NBA Finals
      > > alone.
      > > > That plus a little follow-up was good enough to last 15 years, I
      > > > guess.
      > >
      > > I'm not so sure I really trust all the online play-by-play stuff.
      > > There are definitely errors, ones that I thought were minor, but
      >may
      > > not be. I did sum things up for all 2/14 games and found the best
      > > multiplier for all games. They ranged from 0.22-0.35 with an
      >average
      > > of 0.30 and a std dev of 0.05. At the end of a lot of play-by-
      >plays,
      > > there were funky things happening and occasional gaffes in the
      >middle
      > > of them. If anything, these would appear to lower my counts of
      > > possessions.
      > >
      > > Basically, the estimate formula using 0.4 ends up an average of
      >about
      > > 2% too high (91 poss vs 89 poss actual). If this is true,
      >estimates
      > > of team offensive and defensive ratings are about 2% too low. But
      > > I'm not sure if I trust things yet. Gotta score some games.
      > >
      > > DeanO
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