Coach Bill Belichick: A Statistical "Hoodie" Analysis, Part 1

Guest Blogger 27 June, 2013

Bill Belichick in a rare, non-hoodied moment. by Bob Yoon, guest blogger

As a longtime Boston sports fan, these past 12 years have spoiled me for the rest of my life—seven titles amongst all four of the major sports teams and over 30 playoff berths. This era of dominance began with the New England Patriots, and the one man at the center of the team’s ascent to greatness is Coach Bill Belichick. Over the years, his choice in wardrobe has garnered just as much attention as his mastery of football strategy and tactics. His grey hoodie with the cutoff sleeves has become synonymous with his savvy, if eccentric, football acumen. 

Recently, with the offseason lull between minicamp and training camp looming, a noted Patriots blogger named Mike Dussault (@PatsPropaganda) wondered aloud via Twitter:

Suddenly, visions of hypothesis testing via Minitab Statistical Software leapt into my mind, and I responded to Mike immediately after seeing his tweet. We began exchanging emails. Mike and I put together a data collection strategy through a shared Google spreadsheet. I asked for the following columns:

What BB wore
Points scored
Points allowed
Anything else Mike wanted to add

Mike then spent a considerable amount of time trying to figure out what the coach wore for each game. He scoured through archival footage of games, press conferences and even crowdsourced on Twitter. In the end, he had an answer for 160 out of about 180 games. The spreadsheet can be found here. As you can see, the spreadsheet was not in a Minitab-friendly format:

google spreadsheet

Also, I decided to find a primary metric that was continuous in order to keep things as simple as possible for the analysis. I determined that “point difference” ( Patriots score minus the opponent’s score) would be the best metric for this. Ultimately, my first Minitab worksheet looked like this:

Minitab worksheet

I cannot think of another active coach in all of sports whose wardrobe choices are discussed as much as Belichick’s. Some natural hypotheses came to mind immediately. Some of the most notable losses in the Patriots’ history came when Belichick wore something other than his grey hoodie.

Before the start of Super Bowl XLII, many of us gasped audibly when we saw the coach come out in a red hoodie.  

The rest of that game is history – and one of the greatest upsets in professional sports. Mike and I had this in the back of our minds when I embarked on analyzing this data.

First, let’s look at the iconic grey hoodie. According to our data, Coach Belichick first donned the grey hoodie in 2003, the season when he won his second Super Bowl. He began cutting off the sleeves in 2005. In 2012, the NFL switched from Reebok to Nike, so Belichick had to start wearing a new Nike hoodie. Are there any differences associated with these changes?

I first looked at the Nike grey hoodie versus the Reebok grey hoodie. There weren’t enough samples of the Nike hoodie for me to use a Two-Sample T-Test, so I used a Two Proportions Test based on wins:

Test for Two Proportions

When I looked at the grey hoodie with sleeves vs. without, I was able to run both a Two-Sample T and a Two Proportions test:

Two-sample T-test

Two Proportions Test

Since all three hypothesis tests failed to reject the null hypothesis, we could not conclude that there was a difference in Patriots wins for Nike vs. Reebok grey hoodies, or for sleeved vs. sleeveless grey hoodies.

The connection between wins and Belichick’s sartorial choices had to depend on something other than hoodie manufacturer or the presence of sleeves. So I started a new worksheet, combined all those factors under “grey hoodie,” and prepared for my next analysis...which I'll share tomorrow.


About the Guest Blogger:

Bob Yoon is a certified Lean Six Sigma Black Belt and has been a continuous improvement engineer at Kraft Foods in Champaign, Ill. since 2011. He is committed to promoting and leading continuous improvement in his work and is a dedicated Boston sports fan. Bob can be reached on Twitter at @patscognoscente.


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Photo by Keith Allison, used under a creative commons 2.0 license