Now that the regular season is over, let's take a look at the numbers and see if there is a statistically significant change in NFL regular season home game attendance. First, the numbers. Using the NFL attendance data from Pro Football Reference, I looked at the 2002 to 2017 NFL regular seasons. This is a time period where the number of teams remained constant at 32 (even though some teams moved cities or stadium capacity changed). Given the relative stability during this time period, it is easier to make season to season comparisons. As you can see below, 2016 had the highest total regular season home game attendance, followed by a rather large decrease in 2017. Also notice, that NFL regular season total home game attendance increases and decreases from season to season.
Let's look at that dip from 2016 to 2017. That represents a decline of 535246 total fans for the 2017 season as compared to the leagues high water mark in 2016. Over half of the decline is due to the Los Angeles Chargers playing in a much smaller stadium that in the past. The Los Angeles Rams, the Cincinnati Bengals and the Washington Redskins also had sharp declines in total home game attendance. Of the 32 teams, 22 had declines in total home game attendance, 9 had increases in attendance and 1 team (Philadelphia) had no change in total home game attendance as compared to 2016. In percentage terms, attendance is down 3.1% from 2016 overall, and taking out the LA Chargers, total home game attendance is down 1.6%. There is no doubt that NFL regular season total home game attendance is down from 2016.
But other seasons have seen declines in home game attendance, even without NFL player national anthem protests. So a decline in attendance from one season to another is not unusual. What I want to know is if this decline is unusual as compared to the ups and downs of NFL regular season team home attendance, and the way to determine that is if the team's home attendance is statistically different from last season to this season.
To do that i will use a statistical technique called a t-test. Specifically, I am using a paired, two-tailed t-test; paired since the same teams have been in the NFL since 2002 and two-tailed since attendance can go up or down for each team from one season to the next. A t-test is a statistical technique that compares the means of two variables and tells us if they are different from each other, and lets us know if they are significantly different as opposed to them happening by chance. Statistical significant is the way to judge whether the results are meaningful. In general we use an error rate less than 5% (p value <=0.05) to judge whether two variables (like NFL team home game attendance from one season to the next) are different from each other. We choose a low error rate to avoid Type I error, which is to incorrectly conclude the existence of something that does not exist.
So what are the results? First, from 2002 to 2016, none of the paired, two-tailed t-tests for NFL team home attendance are statistically significant. Even the "great recession" of 2007 to 2009 did not yield a statistically significant difference in NFL team regular season home game attendance, even though we see attendance declining during that time period. If something that large did not impact the NFL team regular season home game attendance, would a fan boycott?
Using the same paired, two-tailed t-test, I find that team regular season home game attendance was not statistically significant, and as such I cannot conclude that the NFL players protests during the national anthem lead to a decline in attendance as opposed to NFL team regular season home game attendance decreased due to random chance.