Analysis of Fouls - The Final Chapter

If you recall, our last episode concluded with quite a cliff-hanger.  There were some rather murky, quasi-conclusive statistics indicating that, at least for the 2009-2010 season, there seems to be a disparity in Personal Foul Differential in favor of large-market teams when they play small-market teams.  Conspiracy!!!!11

Naturally, like any good statistician or politician, I qualified my findings by saying that further study on a much larger dataset would be required in order to definitively claim an anti-small-market bias.  Of course, I don’t have the time to go and mine that much data from the interwebs.  So, I went and did it anyways.

I am currently in possession of a database of the 11,449 regular-season games played from the start of the 2000-2001 season through Jan 10, 2010.  Run this much more comprehensive dataset through the Data Analyzer Engine v2.1™, and here’s the home-court PFD chart that gets spit out:



Huh.  Pretty much the inverse of what all the conspiracy theorists would predict.  Over the past ten years or so, small-market teams have actually enjoyed a significantly higher home-court advantage in PFD – an advantage that is at its greatest when hosting large-market teams.  In fact, if you look at all the numbers, you can detect a fairly well defined inverse correlation between market-size matchups and home-court PFD. 

Want to know how different markets perform on the road?  Read the chart in the other direction, and look at the numbers as the away team’s visiting-court disadvantage.  So, a small-market team visiting a large-market team only gives them 0.32 fouls per game – far less than the 0.69 league average.  And regardless of opponent, visiting large-market teams give away more fouls per game to their host (0.81) than small-market visiting teams do (0.47).

Needless to say, I won’t be firing a missive at David Stern’s office anytime soon, lest he try to correct the situation and take away our small-town advantage.

But what if you consider all games, home and away, and how the markets match up?  Ask, and ye shall receive…



Again, it appears that small-market teams have an overall historical advantage in PFD when compared to mid-market and large-market teams.  In fact, small-market teams as a group average a positive PFD against all opponents, while mid-market and large-market teams give fouls away!

I think at this point I feel comfortable saying that there is no evident league or referee bias in favor of large-market teams vs. small-market teams, at least as far as regular-season PFD is concerned.

If you’re interested, here’s a breakdown of the home-court advantage of each team over the past ten years or so:


Okay, so we’ve established that there is no correlation between market size and PFD (at least, not one that we small-market fans want to get too vocal about).  And, we can clearly see a defined home-court advantage in PFD.  How has star power impacted PFD over the past 10 years or so?

As hard as I tried, the best archival PER data that I could find for the years in question only showed the top 20 players for each year (as opposed to the top 50 used in my earlier 2009-2010 analysis).  Knowing that this reduced dataset will tend to blunt the results somewhat, I calculated each team’s cumulative top-20 PER for each season since 2000-2001 and then averaged each team’s seasonal results.  I then made a chart comparing the PER results to each team’s PFD for those years, and just for kick and giggles I tossed in each team’s win percentage as well.

The chart below is sorted in descending order by top-20 PER.  I have highlighted the top ten in each category green, and the bottom ten red(ish).


As you can see, there are definite correlations between a team’s star power, PFD, and win percentage.  However, the correlation seems to be much stronger between star power and win percentage – the top five "star power" teams of the past decade are among the top ten winningest teams of the past decade.  Similarly, the bottom five "star power" teams are all in the bottom third of all teams by win percentage.  There does appear to be a correlation between star power and PFD – though not nearly as strong as the correlation with win percentage. 

What does this all mean?  To me, it reinforces the obvious.  The teams with the best players win.  Do they get more foul calls?  That may appear to be the case.  Does that affect the outcome of games?  Probably.  Does this mean that the refs, and by extension their employer (the League), are biased in favor of star players?  Maybe.

Is that a problem that needs to be fixed?  I don’t think so.  It’s just the nature of the business of basketball.

So what does a team have to do to get the refs in their pocket?  Move to a major market?  Nope.

Go.  Get.  The.  Players.

(This is a FanPost from a member of the Sactown Royalty community. The views expressed come from the member, and not Sactown Royalty staff.)

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