Re: Home Team Assist Bias
- I actually covered this briefly in the Prospectus. Memphis'
scorekeeper gave him assists like it was Halloween candy.
--- In APBR_analysis@yahoogroups.com, "harlanzo" <harlanzo@y...>
> --- In APBR_analysis@yahoogroups.com, "Dean Oliver" <deano@r...>at
> > My take on home court bias in reffing or scoring is this: you
> > tell whether it's home court bias or just players playing better
> > home. Is there any way to really distinguish between these?
> > DeanO
> I'd be interested to see how the white Jason Williams home assists
> changed when he went from Sacramento to Memphis. It was rumored
> that Memphis' official scorer was exceedingly generous.
- They did the same thing to Webber last year after the Sac scorekeeper
gave him a bogus assist to get a triple-double.
--- In APBR_analysis@yahoogroups.com, "Dean Oliver" <deano@r...>
> Thanks, Mike, for clarifying what I had little time to explain.
> yes, Hakeem did have an assist taken away. They do review such<tamada@o...>
> things, though I don't know the full process.
> --- In APBR_analysis@yahoogroups.com, "Michael Tamada"
> > -----Original Message-----
> > From: Mike G [mailto:msg_53@h...]
> > Sent: Sunday, November 02, 2003 3:29 PM
> > --- In APBR_analysis@yahoogroups.com, igor eduardo küpfer
> > <igorkupfer@r...> wrote:
> > >> Has this been covered?
> > >>
> > >> Ast/FGmade 02-03
> > >>
> > >> Home Away
> > >> Win 62.4% 59.1%
> > >> Loss 61.2% 57.8%
> > >>
> > >> Seems like pretty clear bias against the visitors to me.
> > >
> > >Granting assists more liberally to the home team (almost 6% more
> > >generous, win or lose) might cause someone to think differently
> > >about a player -- unless they know of this bias.
> > >
> > >It's statistically significant, but it doesn't seem important,
> > >otherwise. Guys play half their games on the road, so there's
> > >overall advantage.found
> > >
> > >However, if someone points out that Jamal Crawford gets 5% more
> > >assists at home, and therefore he should play fewer minutes in
> > >games, they are apparently mistaken. That's just par for the
> > >course: everyone gets 5-6% fewer assists on the road.
> > All good points, although I would also take DeanO's point and
> > drive it even further: it's possible (unlikely, but possible)
> > that those stats reflect no bias at all, but instead are REAL.
> > I.e. maybe visiting teams have fewer assists, percentage-wise,
> > than home teams. We know already that the visiting teams are
> > more likely to lose, and will score fewer points. Maybe they
> > rely more on one-on-one offense to score. Maybe they get
> > fewer fastbreaks and thus fewer chances for a Payton to pass
> > to a streaking Kobe for a layin.
> > A similar statistic: I believe that researchers have already
> > that home teams get more Free Throw Attempts, and are called forstrong
> > fewer fouls, than visiting teams. Is that due to ref bias? Or is
> > it because the home teams literally are commiting fewer fouls?
> > In the case of fouls, my guess is that most of the home-road
> > differential is caused by real differences and not ref bias.
> > In the case of assists, I'd guess that home scorer bias is a
> > and quite possibly primary factor, but I don't think we have
> > evidence to come close to proving this.
> > I'd have to think that the NBA has quality control measures for
> > its scorekeepers and statkeepers, and looks at video tapes to
> > see if assists are being awarded properly (didn't the NBA take
> > away a bogus home quadruple-double from Hakeem or someone like
> > that, after determining that the home statistician had been
> > over-generous in awarding assists -- or maybe it was even
> > a phantom rebound)? So the NBA probably does have true
> > comparative home and road stats. Whether it has found a
> > home-road difference, how large it is, and how much effort
> > the NBA is putting into eradicating it -- those are open
> > questions.
> > --MKT