Wednesday, February 1, 2017

NFL television ratings, or the lack thereof

The viewership of the 2016 NFL regular season was lackluster to say the least.  The television ratings seemed to stumble out of the gates in September.  This prompted several public responses from commissioner Roger Goodell, attempting to explain away the downturn in viewership - he pointed the finger at everything from baseball playoffs to the extended coverage of the presidential election.

I want to review some facts of television and some of the metrics the industry uses to quantify their success.  I will show that the NFL, and similar media, have an upward battle to gain back the lost viewers.  They are "swimming against the stream" - figuratively and literally.  The first part will discuss what really happened to the NFL in 2016.

Some background information you will need:
  • television ratings = (# of TVs watching program X) / (# of TVs)
  • viewers = (# of TVs watching program X) x (# of people watching per television)
  • the NFL has three prime time broadcasts three each week of its season (17 weeks per season):
    • Sunday Night Football (SNF),
    • Monday Night Football (MNF), and;
    • Thursday Night Football (TNF).

I have collected data on the ratings and viewers of each of the prime time NFL broadcasts for the 2014, 2015, and 2016 seasons from Sports Media Watch.  For purposes of exhibition, I focus on SNF, which is the most watched of the three prime time games with an average rating of around 12 (MNF and TNF both have an average rating of around 8).  SNF has had the greatest ratings of any Fall show since 2010 (as per TV by the Numbers).

I want to see how different the viewership was in 2016 when compared to 2015, if at all.  I begin by plotting a three-week moving average of the number of viewers of each SNF game in these two years, as shown below.  Focusing on the solid black line, the 2015 season started with an average of around 25 million viewers for the first three weeks and finished with an average of 20 million viewers in the final three weeks.  By contrast, the 2016 season, the solid yellow line, started with an average of 22 million viewers and ended with an average of 24 million for the first and last three weeks respectively.  Up until week eight, the 2016 season's viewership looked bleak.

Now consider a similar broadcast: The Walking Dead (TWD).  TWD also airs during Sunday prime time and has 16 episodes to each season, comparable to the 17 SNF broadcasts per season. Also noteworthy is that TWD is the top-rated, non-sports broadcast.  The dashed black and yellow lines in the figure above illustrate the similarity in the trends of viewership for TWD and SNF (TWD data also comes from TV by the Numbers).  This exercise is the first indication that the 2016 downward trend in viewership may not be unique to the NFL.

Returning our attention to the NFL, a superficial explanation may suggest the ratings of the 2016 season are a result of poor scheduling choices or uneventful play.  In order to test this theory, I turn to a measurement of the relative competition in each match-up: FiveThirtyEight's Elo.  This gives a relative value of the skill level of each team prior to a particular game, where higher values indicate higher skilled teams.  I run a simple regression of viewership as follows:

(1) viewersi,j,e= f(Elo+ Eloj, evente)

where Elo+ Elois the sum of the Elo scores of each team and eventis an indicator of which prime time game is being played: SNF, MNF, or TNF (note that I have chosen SNF to be the base).

I use the 2014 and 2015 NFL seasons to predict viewers for the 2016 season.  I then plot the residuals by week as shown below.  The black crosses show how the 2016 viewership fared against the model: points above the zero line indicate that the number of viewers was higher than predicted value given the level of competition of the match.  As the narrative suggests, many of the 2016 points lie below the zero line suggesting that the actual viewership did not live up to expectations.

I have highlighted two weeks in particular: five and eight.  These two SNF games were broadcast under exceptional circumstances: during the 2nd presidential debate and a Major League Baseball World Series (playoff) game.  These two games were aired simultaneously with strong substitutes, yet other weeks during the 2016 NFL season equally under-performed their respective expected viewership.  In other words, baseball and politics do not fully explain away the low NFL viewers.

I rerun equation (1) and add in season fixed effects and then, separately, control for team fixed effects.  The team effects are a set of dummies, one for each of the 32 teams, that take the value of one if that team is participating in the match.  These results are shown below.

Variable Model 1 Model 2
Sum of Elo 7.50*** 1.03***
(5.20) (5.09)
SNF -base- -base-
MNF -7.51*** -6.55***

(-14.34) (-13.14)
TNF -12.12*** -10.26***

(-20.00) (-12.60)
Year is 2014 -base- -base-
Year is 2015 0.23 0.25

(0.57) (0.79)
Year is 2016 -1.25*** -1.38***

(-2.64) (-3.53)
Team FE No Yes
Constant -2.45 -10.53*

(-0.53) (-1.71)
Adjusted R2 0.83 0.90
Observations 143 143

The results above suggest that in 2016 there was an average of 1.25 million to 1.38 million less viewers per game after controlling for the level of play.  Thus, the 2016 NFL regular season ended with 70 million less viewers than 2015 for it's prime time broadcasts, equating to a 10% decline in total viewership.  However, one thing we are failing to address is if the NFL could have chosen a better slate of games to feature in its prime time broadcasts.  What was the NFL's next-best option?

The 2016 NFL season did have one of the highest rated regular season games of all times between the New York Giants and the Dallas Cowboys.  The success of the aforementioned record-setting game prompted the NFL to change the schedule of the games for the next week to feature the Cowboys in a prime time broadcast again.  The use of the "flexible scheduling" is stated to "[ensure] quality matchups on Sunday night [...] and [give] surprise teams a change to play their way onto primetime.''  The NFL can, in theory, pick which match-ups to feature in nine of the 17 SNF games.

I would like to illustrate how the NFL could have gained from better scheduling.  First, here are the rules of flexible scheduling:
  • In effect between weeks 5 - 17.
  • Max 2 games can be flexed between weeks 5 - 10.

And my assumptions:
  • NFL is risk neutral (prefers to maximize predicted ratings rather than  some sort of trade-off between magnitude of the estimated ratings and the magnitude of the estimates standard error).
  • The is no cost to changing the schedule.
  • Other networks cannot reserve games from being flexed (e.g. FOX wants to air the game on their network instead of going to NBC which hosts SNF).

I run the same models as detailed in the table above and predict the millions of viewers for each of the games that had could have been scheduled to play on SNF  Then I have the model choose the games with the highest predicted ratings to be featured on SNF for that week.  I limit the number of times a new game can be flexed in during the weeks 5 through 10 as per the rules of flexible scheduling.

Using Model 1, we see there would have been seven out of a possible nine scheduling changes.  The results suggest that the NFL could have added an additional 7.1 million viewers by using this more effective schedule.  Note that had the NFL based it's decision making process off of this model, they would never have aired the record-breaking game between the Cowboys and Giants in week 14.  Instead they would have opted for slightly higher expected viewership in the Seattle Seahawks and Green Bay Packers game.

Using Model 2, only five games would have been flexed into SNF which would increase the aggregate number of viewers by 16.2 million.  Recall that Model 2 uses team fixed-effects - this model highly favours teams like the Dallas Cowboys, New England Patriots, Denver Broncos, and New York Giants.  Model 2 suggests that SNF should always feature at least one of the aforementioned teams.


Models 1 and 2 rarely agree.  Although both would suggest the NFL made scheduling errors in weeks 6, 11, 13, and 17, the two models offer conflicting solutions to the problem.  In reality, the cost of changing the schedule may outweigh the benefit of the additional expected viewers.  Ultimately, flexing in more popular games would not have fully reversed the downturn in NFL viewers.

In summary:
  • the 2016 NFL regular season fared poorly in viewership.
    • -70 Million or -10% compared to 2015.
    • this occurred despite the strength of available substitutes airing contemporaneously.
  • there were gains to be made by rescheduling SNF games.
    • 7.1 to 16.2 million viewers in expectation.
  • scheduling would not have completely solved the issue of lost viewers. 
    • 2016 had a unique effect on viewership.
  • similar television programs saw a decline in viewership
Thank you for reading.  Please join me in the next post about television ratings where I will discuss the last point in bold above.  I also promise not to talk about the NFL.  Please add any comments or questions below.

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