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IrishHand

Joined: 15 Jul 2009
Posts: 115

Posted: Fri Aug 21, 2009 6:16 pm    Post subject: Home court scorekeeping bias - blocks

I wanted to look at things from a slightly different perspective, both to look at better numbers and to placate Dean by looking at arena-specific numbers rather than home-team-in-and-out-of-arena numbers.

What better numbers? If I'm concerned about the impact of the scorers, the relevant decision made by them is whether to award a block on each missed shot. (Brought to you by someone far, far smarter than me.) Reason being that missed shots are pretty ironclad, and the block is an optional detail note about what happened on the miss and is solely determined by the stat crew. There's no ref impact on this number.

Why arena-specific? If it is indeed the case that some stat crews are simply more generous across the board, that definitely shifts the debate somewhat.

Specifically, I looked at the % of missed shots that were awarded blocks by the home stats crew in each NBA arena. I then broke them down home and away, and then I determined the percentage deviation from the leaguewide norm for each of those three numbers (total block %, home block %, and away block % - all %s a function of BLK/FGmissed). Finally, as a potential measure of the relative degree of home scorer bias, I determined the difference between home and away block % deviation.

Teams sorted by total B/FGm - so by the overall tendency of the home stat crew to award blocks on misses.

 Code: Total       HmTm    OpTm                   Arena B/FGx      B/FGx   B/FGx      TotDev  HTDev    OTDev      Hbias DEN   14.3%      17.4%   11.5%      30.4%   58.7%     4.6%      54.1% CHA   14.2%      14.5%   14.0%      30.0%   32.3%    27.8%       4.4% LAC   13.4%      14.9%   11.8%      22.0%   35.9%     7.9%      28.0% CHI   12.5%      13.8%   11.3%      14.5%   25.8%     3.5%      22.3% GSW   12.3%      15.7%    9.1%      12.6%   43.4%   -17.1%      60.4% IND   12.1%      13.3%   10.9%      10.4%   21.3%    -0.5%      21.8% MEM   11.8%      12.4%   11.0%       7.3%   13.6%     0.8%      12.8% WAS   11.6%      10.5%   12.8%       6.2%   -3.8%    17.2%     -21.0% UTA   11.6%      11.4%   11.8%       5.9%    4.1%     7.6%      -3.5% DET   11.4%      11.9%   10.9%       4.1%    9.0%    -0.9%       9.9% NJN   11.2%      10.8%   11.6%       2.1%   -1.1%     5.5%      -6.6% TOR   11.2%      12.1%   10.3%       1.9%   10.4%    -6.2%      16.6% CLE   11.2%      13.8%    8.8%       1.9%   26.3%   -20.0%      46.2% BOS   11.1%      12.4%   10.0%       1.5%   12.9%    -8.7%      21.6% LAL   11.1%      13.3%    9.0%       1.2%   21.7%   -18.1%      39.8% HOU   11.0%      10.8%   11.3%       0.9%   -1.8%     3.3%      -5.1% MIN   10.9%       8.1%   14.0%      -0.9%  -25.7%    27.7%     -53.4% DAL   10.7%      13.3%    8.2%      -2.1%   21.9%   -24.9%      46.8% OKC   10.6%      10.7%   10.6%      -2.8%   -2.0%    -3.6%       1.5% PHX   10.4%      13.7%    7.6%      -5.1%   25.1%   -30.2%      55.3% PHI   10.3%      11.9%    8.8%      -5.8%    8.3%   -19.8%      28.1% POR   10.3%      12.8%    7.9%      -5.9%   16.5%   -28.3%      44.8% MIA   10.2%      13.0%    7.5%      -6.7%   18.9%   -31.9%      50.8% SAC   10.1%       9.6%   10.7%      -7.4%  -12.1%    -2.3%      -9.8% ORL    9.7%      13.2%    6.6%     -11.5%   20.6%   -39.9%      60.4% SAS    9.2%       9.9%    8.7%     -15.6%  -10.1%   -20.8%      10.8% NOH    8.7%      10.2%    7.2%     -20.7%   -6.5%   -34.5%      28.0% MIL    8.6%       8.2%    9.1%     -21.3%  -25.3%   -17.2%      -8.1% ATL    8.5%      10.1%    7.0%     -22.4%   -7.8%   -36.0%      28.2% NYK    7.2%       4.6%    9.9%     -34.2%  -57.6%    -9.6%     -48.1% TOTAL 11.0%      11.9%   10.0%       0.0%    9.1%    -8.8%      17.9%

Total B/FGx - percentage of missed shots that were awarded a block by the home stat crew in that arena
HmTm B/FGx - above, for home team blocks of away misses
OpTm B/FGx - above, for away blocks of home misses
TotDev - % deviation of Total B/FGx from league average (11%)
HTDev - % deviation of HmTm B/FGx from league average (11%)
OTDev - % deviation of OpTm B/FGx from league average (11%)
Hbias - HTDev-OTDev

Initially, it is clear that the data contradicts the suggestion that the increased incidence of home-team-blocks is due to some teams just awarding more blocks as a general matter. While this appears to be the case in Charlotte and, to a lesser extent, Utah, a significant majority of the teams that award blocks at a rate higher than the league average are doing so to the distinct advantage of the home team.

Much discussed-Denver is the easiest case. Yes, they do award the most blocks in the NBA on a per-missed-shot basis. However, the opponent isn't benefiting much at all from this generosity, garnering only 4.6% more blocks than league average. Denver players, however, are getting 58.7% more blocks than the league average. Now, if Denver boasted an exceptional shot-blocking team, this might make sense. However, as noted in the other thread, Denver is just a bit above league average in BPG when they're away from the very friendly confines of the Pepsi Center.

It seems from the data that a few teams are underreporting away blocks, but that the bigger trend is to overreport home blocks when you have one or more legit shot-blockers.

To be fair, I think the comparison of blocks at home and on the road as prima facia evidence of home crew bias is more compelling. I do think the above data refutes the notion of "well, this team just gives out more blocks, they aren't just padding their own player's totals" though.

Alex

Note: Edited for column labelling per Mike's request. No change to text/numbers.

Last edited by IrishHand on Sat Aug 22, 2009 7:49 am; edited 1 time in total
Ryan J. Parker

Joined: 23 Mar 2007
Posts: 708
Location: Raleigh, NC

Posted: Fri Aug 21, 2009 6:35 pm    Post subject:

Could you give an example of how you calculate:
 Code: TotDev - % deviation of Total B/FGm from league average (11%) HTDev - % deviation of HmTm B/FGm from league average (11%) ATDev - % deviation of AwTm B/FGm from league average (11%)

I'm having a tough time using my skillz to re-produce these numbers (unless there is some rounding error).

That being said, why use these calculations instead of simply subtracting HmTm B/FGm from the league avg? A number like 17.4%-11.9%=+5.5% for Denver at home means more to me than +58.7%. I seem to be missing the point in the reasoning behind the calculations that give us these numbers. Perhaps knowing exactly how they're computed will help clear it all up for me.
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IrishHand

Joined: 15 Jul 2009
Posts: 115

Posted: Fri Aug 21, 2009 6:49 pm    Post subject:

17.4% / 11.0% (league average for all misses) = 58.7%
(And yes, the numbers in my spreadsheet go several decimals deep so the math won't work perfectly w/ the rounded numbers posted.)

11.9% is league average for home - not a good number when the hypothesis is that there is home bias in most arenas. The 11.0% is certainly a better number - though I think there are compelling reasons for using the road average of 10%.

Also...since it helps to put the numbers in context, I've included the basic numbers along with the numbers that the Home team gets on the road (Away B/FGm).

 Code: Total      HmTm   OpTm      Away Arena B/FGx      B/FGx   B/FGx     B/FGx DEN   14.3%      17.4%   11.5%      11.1% CHA   14.2%      14.5%   14.0%       8.7% LAC   13.4%      14.9%   11.8%      10.8% CHI   12.5%      13.8%   11.3%      10.7% GSW   12.3%      15.7%    9.1%      12.1% IND   12.1%      13.3%   10.9%       9.2% MEM   11.8%      12.4%   11.0%      10.0% WAS   11.6%      10.5%   12.8%       9.4% UTA   11.6%      11.4%   11.8%      10.1% DET   11.4%      11.9%   10.9%       9.2% NJN   11.2%      10.8%   11.6%      11.0% TOR   11.2%      12.1%   10.3%       9.5% CLE   11.2%      13.8%    8.8%      11.8% BOS   11.1%      12.4%   10.0%      11.5% LAL   11.1%      13.3%    9.0%       9.4% HOU   11.0%      10.8%   11.3%       9.2% MIN   10.9%       8.1%   14.0%       9.0% DAL   10.7%      13.3%    8.2%      10.4% OKC   10.6%      10.7%   10.6%       9.2% PHX   10.4%      13.7%    7.6%      11.5% PHI   10.3%      11.9%    8.8%      11.8% POR   10.3%      12.8%    7.9%      10.4% MIA   10.2%      13.0%    7.5%      12.0% SAC   10.1%       9.6%   10.7%       9.2% ORL    9.7%      13.2%    6.6%      12.2% SAS    9.2%       9.9%    8.7%       9.0% NOH    8.7%      10.2%    7.2%       9.5% MIL    8.6%       8.2%    9.1%       8.2% ATL    8.5%      10.1%    7.0%      11.4% NYK    7.2%       4.6%    9.9%       5.6% TOTAL 11.0%      11.9%   10.0%      10.0%

Note: Edited for more column label changes. No text/numerical changes.

Last edited by IrishHand on Sat Aug 22, 2009 7:50 am; edited 2 times in total
Ryan J. Parker

Joined: 23 Mar 2007
Posts: 708
Location: Raleigh, NC

 Posted: Fri Aug 21, 2009 6:53 pm    Post subject: You're right, I meant to use 11.0% for +6.4%. What exactly is +58.7% telling me over +6.4%? That +58.7% doesn't seem to be very tractable. Why would I prefer this number to +6.4%?_________________I am a basketball geek.
IrishHand

Joined: 15 Jul 2009
Posts: 115

 Posted: Fri Aug 21, 2009 7:00 pm    Post subject: A +6.4% increase in total numbers is a 58.7% increase in blocks. I guess I'm more concerned with the latter than the former, though they both relate to the same thing (as you noted).
HoopStudies

Joined: 30 Dec 2004
Posts: 705
Location: Near Philadelphia, PA

Posted: Fri Aug 21, 2009 7:06 pm    Post subject:

FYI - There is an established method for evaluating Arena Factors, based on baseball's park factors:

AF_blk = (Blkrate + OppBlkRate)H/(Blkrate + OppBlkRate)R

So you sum the rates at home and divide the total by the sum of rates on the road.

 Code: Tm   AF_blk atl   0.718 nyk   0.766 mil   0.803 mia   0.853 phi   0.867 san   0.887 pho   0.911 orl   0.923 min   0.931 nor   0.946 sac   0.949 bos   0.951 uta   0.958 por   0.961 gsw   0.964 okc   0.976 njn   1.006 hou   1.049 mem   1.057 cle   1.059 tor   1.060 dal   1.065 chi   1.066 was   1.077 lal   1.113 ind   1.136 lac   1.213 den   1.222 det   1.257 cha   1.280

So Atlanta gives the fewest, Charlotte the most. It's not terribly different than what you did, but it has an easy interpretation: It's the ratio of how many total blocks are given in one arena vs for the same teams in other arenas.

So you could say that Atlanta's shot blockers are hindered at the start by getting only 72% as many home blocks. As I say, I have no idea how to turn this and other numbers into an assessment of bias.
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Mike G

Joined: 14 Jan 2005
Posts: 3577
Location: Hendersonville, NC

 Posted: Sat Aug 22, 2009 7:10 am    Post subject: Alex, Would it be too much trouble to change all your "FGm" to "FGx", since many folks use FGm to mean 'FG made' ? At some point (2-3 years ago) there was sort of a consensus on this. Further nitpicking, using the term "away" to refer to the visiting team. I've been using 'away' to mean the team of reference when on the road. 'Opponent' describes the other 29 teams faced by said team. Heading the 'team' column by the label "Arena" is definitely a keeper. So, your league average 'bias' of 17.9% is a bit higher than my initial call of 15.3% . Possibly because you adjusted for pace (of FGx), and I just used raw ratios. Meanwhile, Dean's formula looks a bit like one I had lying about. While his takes the ratio of the (H/A) sum, I took the ratio of the ratios: (TmHBlk/OpHBlk) / (TmABlk/OpABlk) Here, (for example) Denver's OpHBlk refers to opponents at Denver, and OpABlk refers to their blocks away from Denver. Portland got just .97 of their opponents' blocks on the road, but 1.64 as many at home. The ratio (1.67) leads the league. Average is 1.34, and no team is below 1.01 ._________________` 36% of all statistics are wrong
IrishHand

Joined: 15 Jul 2009
Posts: 115

 Posted: Sat Aug 22, 2009 7:52 am    Post subject: Mike: fixed/changed. Always happy to comply with naming conventions.
DJE09

Joined: 05 May 2009
Posts: 148

 Posted: Sun Aug 23, 2009 9:16 am    Post subject: How much of this is natural variability? The problem with quoting the home and road team Blk% as a % of league total is the large degree of variation. Further, by comparing everything to the league average you are stating the we expect the home team block rates to be the same as the away teams ... I can't accept that. So how to progress: I went through your charts and got every Blk% that is outside 2 SDs for the average value for that column: That is NYK and DEN and CHA from Arena Blk%; DEN and NYK Hm Bk%; MIN and CHA in Op Bk%; and NYK in Away Bk%. That's it. But then I would expect 1 team to lie outside this range. For each of the 4 columns I get 8-9 teams outside 1 sd - which is exactly what one might expect from natural variability. The biggest outlier is not Denver's 17.4% Hm Bk%, but NYK's 4.6% (seen in change in variance). And the discrepancy between Denver's 17.4% at home and 11.1% on road doesn't seem more eggregarious as the Home-Oppt of 13.2 to 6.6% in ORL, or the 8.1 to 14% observed in MIN ... In conclusion, I think these statistics show the expected natural variability of normally distributed measures, and evidence that we can't conclude there is home court bias.
IrishHand

Joined: 15 Jul 2009
Posts: 115

Posted: Sun Aug 23, 2009 11:54 am    Post subject:

There's a sample size of over 3000 missed shots in every home arena.

 Quote: Further, by comparing everything to the league average you are stating the we expect the home team block rates to be the same as the away teams ... I can't accept that.

Why? If the hypothesis is that most home team rates are higher they should be (or would objectively be with firm scoring standards w/ league oversight) because home scorers pad the stats of shot-blockers, I'd disagree with using the average home rates. I think the most compelling argument is in favor of using average away block rates, since those are the least likely to be tainted by bias and are almost certainly the closest to actual blocks being awarded. (To be fair, the away number is probably inflated a bit too - but that inflation is probably negligible.)

 Quote: I think these statistics show the expected natural variability of normally distributed measures

I suppose this is where I think it's important not only to look at the numbers, but to apply a basic understanding of the game as well.

A team like NY lacked any shot blockers and had 50% fewer shots than any team in the league. They awarded their opponents blocks on 9.9% of Knick misses - or right next to the opponent average of 10%. The data suggests that Knick scorers are unbiased when it comes to blocks (and the hypothesis would have supported this too, since they lack anyone obvious to award extra blocks to). Their best shot blocker was a SF who earned 0.5 bpg the prior year.

Denver, on the other hand, was awarded blocks at around the league average rate when they were on the road (11.1%). This data point suggests that they are an average NBA shot-blocking team. Their Denver arenas scorers awarded their opponents blocks on 11.5% of Denver misses - slightly above-average, but consistent with the fact that Denver takes the 3rd most close shots in the NBA - and close shots get blocked at the highest rate of all shot attempts. At the other end of the "easy to explain" spectrum, we have Denver's 17.4% home block rate, highest in the NBA. They block shots at a rate 59% higher than the NBA average and 55% higher than they do on the road. I'm still waiting for anything resembling a palatable explanation apart from a hefty dose of scorer bias with a hint of ref bias and "playing better".

The Charlotte scorers appear to simply be extremely generous with blocks. They conform to Dean's proposed hypothesis that some teams' scorers simply overreport a stat generically. The Bobcats are a well-below average shot-blocking team on the road (3rd worst in the NBA), yet they're beasts at home (4th in the NBA) - but so are their opponents. I think there are a few possible explanations, none of them particularly good - either Charlotte's scorers are bad at their jobs and just award blocks anytime they think there might have been a block...or they are jacking their own team's blocks and their players get legitimately blocked at a rate far higher than the league average (possible since they take a lot of close shots and aren't a particularly effective offensive team - note that Gerald Wallace and Emeka Okafor lead the league in getting-blocked-% w/ over 12% each).

MIN is much like NY - they generally lack shot-blockers (esp once AlJeff went down)...and to compound their inevitable OpBlk>HmBlk, they take a fair number of inside shots, and they do it with undersized posts. Both Love and AlJef are in the top 15 in the league in getting blocked %. MIN's H/A splits are fairly close (8.2/9.0)...the outlier (opponent blocks in MIN) is readily explainable.

The bottom line to me is that the data I posted doesn't pretend to be a self-contained analysis that one can draw conclusions from. It's merely a set of data points that one could factor into the others that are readily at hand. If Denver was sporting Wade+Granger+JoshSmith+Camby, I would expect them to have Blk%s which led the league by a significant margin home and away. There is no rational explanation that I'm aware of that can support the numbers and splits that they do have, however. The evidence points to them being a slightly-above-average shot-blocking team that benefits from some very subjective home scoring.

The conclusion that I would reach from the above data and a decent awareness of offensive styles and team personnel is:

Teams with significant home bias in their block figures:
DEN, CHA, LAC, CHI, GSW, IND, MEM, DET, TOR, CLE, LAL, DAL, PHX, POR

Teams with less or no home bias in their block figures:
WAS, UTA, NJN, BOS, HOU, MIN, OKC, PHI, MIA, SAC, ORL, SAS, NOH, MIL, ATL, NYK
DJE09

Joined: 05 May 2009
Posts: 148

Posted: Mon Aug 24, 2009 2:13 am    Post subject:

 IrishHand wrote: There's a sample size of over 3000 missed shots in every home arena.

But only 370 blocks (on average, more in DEN, less in NYK). And then you are breaking them down into home and away. Since Blocks are a 'rare' event, we should expect quite a high variability in the Block % statistic.
IrishHand wrote:
 Quote: Further, by comparing everything to the league average you are stating the we expect the home team block rates to be the same as the away teams ... I can't accept that.

Why? If the hypothesis is that most home team rates are higher they should be (or would objectively be with firm scoring standards w/ league oversight) because home scorers pad the stats of shot-blockers, I'd disagree with using the average home rates.

But we all think teams play better at home. They win more games, shoot the ball better, rebound more and foul less ... but now we can't expect them to Block better?

Remember this whole discussion is about pinning down some quantify-able proportion of blocks that can be assigned as due to home bias.

 Quote: I suppose this is where I think it's important not only to look at the numbers, but to apply a basic understanding of the game as well.

I agree that the numbers have to make basketball sense, but I am also aware that blocks are a rare event, only done freqently by a minority of the league. Further, I would expect the natural variability to have a basketball basis - ie. some teams / players are better / generated more blocks than others.

You raise a very good point of shot location, and possibly this is a big factor. I am not sure I have the numbers to look into how these are affecting home and away Blk%.

But back to the Arena/Team analysis.
New York were a poor shot blocking team, but they managed to block 1% more shots on the road than at home (or 20% more - but this is not a good way to analyse small ammounts). Apparently this fact is not evidence that NYK scorers are biased against their home team ... because? the only apparent answer is "I don't think this happens".

Remember your objective here is not to convince me that the home bias occurs, but to put some sort of figure on it. Whatever logic you use, should be able to be applied consistently to all teams - even ones like Atlanta and NYK that appear to be penalising their team.

Orlando owns the best shot blocker and finisher at the rim in the league, so we might expect their numbers from a basketball sense. Except their opponents have a much higher block % (9.25%) when they are playing at home compared to the 6.6% we observe in Orlando. So perhaps Orlando display home court bias by not giving out blocks to their opponents - can Orlando's opponents be that much better at blocking ORL shots when they are playing at home fore basketball reasons?
Further, Dwight Howard records 10% MORE blocks on the road, so Orlando's Home / Away of 13.2 to 12.2 says ORL block 1% more total shots, when their primary shot blocker blocks less shots ... I would think both of these facts together would be enough to convince me there was some home court bias in Orlando.

[Yes, Yes, I can hear you all shouting now, that is all due to the referee's suspect calls]

Remember, your objective is not to convince me that home scorer bias exists ... it is to give some evidence of how much it is changing the numbers, how we disentangle it from the effect the referees have on the outcome of the game. I think we have all pretty much agreed that it happens (as well as the fact the "Home town calls" exist). The open question is what sort of adjustment do we need to make, how much, and to which teams / players?

Using Dean's Block ratio, we can see there is a large degree of variability of the rate that blocks are awarded by venue. One interpretation of this number is the natural variability in the interpretation of what constitutes a block. It is evident that this variability is exhibited in the opponent Blk percentages as well, ie just because there is no correlation between Home and Opponent block % magnitude does not mean all the variability in Dean's statistic is due to the Home Block %.

Let's go back to Denver. They have an Away Bk% of 11.1 - Above the League average 10% (You have to compare it to the Away rate) - so they are an above average shot blocking team on the road: Let us assume that this ratio gives us a "True" measure of Denver's shot blocking ability. At home their crew award blocks to opponents at an above average rate - let us call this the "Definition Bias" and use Dean's figure of 1.222 for DEN. Further, teams perform better at home - ie. I believe that there is a real difference in the rates for a team playing at home, as opposed to on the road. Just for argument's sake let us pretend the "true value" of the legue average home block % is 11.9 (as opposed to the road 10%). Then we could Estimate an expected Denver Home block % of
 Code: 11.9  *  (11.1)/(10) * 1.222 = 16.1 %

This is not 17.6%. But it would still make them the best team in the league at blocking shots.

Of course, I haven't allowed for the fact that denver plays 2 bonafide shot blockers almost all the time, nor where they play ... A quick poll just revealed 87.6% of visiting players believe their performance is adversely impacted by playing in Denver ... Could we expect therefore that the figure of 11.5% which represents the Op.Bk% would be higher if they were performing in a different environment, and so we should adjust Denver's block % up further - possibly as far as 17% ....

I am not saying this is what I think. I think there probably is some home court bias which results in the Denver players being awarded a few (perhaps as many as 1 per home game over the whole team) "Easy" blocks. My problem is how you go about using these numbers or others to determine some sort of adjustment factor that can be uniformly applied - ie. Estimating the amount of home court bias.
Mike G

Joined: 14 Jan 2005
Posts: 3577
Location: Hendersonville, NC

 Posted: Mon Aug 24, 2009 5:16 am    Post subject: Maybe a player should only get credit for a block% at home that's equal to (occasionally less than) his road Blk%. He should therefore be compelled to 'play better' on the road to match what he does at home. If his road Blk% suggests he got 25 'too many' blocks at home, that figure would be subtracted from his alleged season total. This may not be immediately 'fair' to those guys who only play to their potential in front of an adoring crowd, but it would motivate them to greater consistency. As it might motivate scorekeepers, too._________________` 36% of all statistics are wrong
HoopStudies

Joined: 30 Dec 2004
Posts: 705
Location: Near Philadelphia, PA

 Posted: Mon Aug 24, 2009 9:00 am    Post subject: Another thing to consider here is that there is also vagueness when it comes to a block and a defensive rebound vs a steal, especially when a player is starting to go up for a shot. "Is that a shot or a pass?" is also even more frequently confused for whether it is a block/DR or a steal. This occurred to me as I was watching some clips from last year and seeing it happen a few times. I haven't watched enough to get any kind of significance and it's pretty low on my priority list for what I'm looking for. The Nuggets arena, for example, awards many fewer steals at home than are seen on the road (tied for 8th lowest AF in steals), implying that some of the high Arena Factor for blocks is actually just making up for the low Arena Factor for steals. This also would have to be factored in "home bias," though it is more complicated how. It could be that some of those blocks are actually steals, but it's not a bias for a player, just an arena bias for blocks._________________Dean Oliver Author, Basketball on Paper The postings are my own & don't necess represent positions, strategies or opinions of employers.
BobboFitos

Joined: 21 Feb 2009
Posts: 193
Location: Cambridge, MA

Posted: Mon Aug 24, 2009 10:16 am    Post subject:

 Quote: Orlando owns the best shot blocker and finisher at the rim in the league, so we might expect their numbers from a basketball sense. Except their opponents have a much higher block % (9.25%) when they are playing at home compared to the 6.6% we observe in Orlando. So perhaps Orlando display home court bias by not giving out blocks to their opponents - can Orlando's opponents be that much better at blocking ORL shots when they are playing at home fore basketball reasons? Further, Dwight Howard records 10% MORE blocks on the road, so Orlando's Home / Away of 13.2 to 12.2 says ORL block 1% more total shots, when their primary shot blocker blocks less shots ... I would think both of these facts together would be enough to convince me there was some home court bias in Orlando.

Only sorta scanned this post so I may be misreading, but to me it's pretty obvious why Orlando as an opponent yields a much lower blk% - they take more 3s (which have a very low blk rate!) than any other team.

Again, to echo Irishhand, it's all about context. And it's easy to explain why Orlando as an opponent in other arenas yield lower blk rates.
_________________
-Rob
BobboFitos

Joined: 21 Feb 2009
Posts: 193
Location: Cambridge, MA

Posted: Mon Aug 24, 2009 10:17 am    Post subject:

 Quote: The Nuggets arena, for example, awards many fewer steals at home than are seen on the road (tied for 8th lowest AF in steals), implying that some of the high Arena Factor for blocks is actually just making up for the low Arena Factor for steals. This also would have to be factored in "home bias," though it is more complicated how. It could be that some of those blocks are actually steals, but it's not a bias for a player, just an arena bias for blocks.

Do you recommend just smashing blocks + steals together for a larger sample size to seek out bias?
_________________
-Rob
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