Watching the NFL this season has been a bit eerie. The piped-in artificial crowd noise is weird, and the shots of the empty (or near-empty, depending on the location) stadiums really brings home just how far from the norm we are this year.
Large gatherings, including sports events, were one of the first targets of public health authorities trying to contain the coronavirus pandemic. How effective was that approach? A recent working paper by Coady Wing, Daniel Simon, and Patrick Carlin (all Indiana University) provides an initial answer. They study the differences between counties (and metropolitan statistical areas [MSAs]) that hosted more, or fewer, NHL and NBA games between 1 January and 12 March (when both leagues were shut down), in terms of the number of COVID-19 cases and deaths. They also look at the relationship with the number of NCAA Division 1 basketball games.
They find that:
...hosting one additional NBA or NHL game results in an additional 428 COVID-19 cases and 45 COVID-19 deaths in the county where the game was played. This amounts to 783 COVID-19 cases and 52 COVID-19 deaths for the MSA as a whole. There were about 22 NHL and NBA games played in the average MSA. In total, then, these 22 games between January and mid-March resulted in more than 17,000 cases and nearly 1160 deaths per MSA. In contrast, we find that men's college basketball games only resulted in an additional 31 cases and 2.4 deaths per MSA. On average there were about 16 college games in an MSA, resulting in about 496 additional cases and 38 additional deaths per MSA.
Needless to say, those effects are quite substantial. Also:
Using a more conservative (age-adjusted) VSL of $2 million implies that each NLH/NBA game costs about $104 million in fatalities, and each NCAA game costs about $5 million in fatalities... Using this more conservative VSL, our results indicate that the roughly 22 NHL and NBA games played in January-mid March created about $2.3 billion worth of fatalities per MSA, while the roughly 16 NCAA games created about $80 million worth of fatalities per MSA...
...fatality costs per game ($104 million) are nearly 40 times greater than spending per game. Even assuming that total consumption benefits are four times greater than spending (i.e., $3 of consumer surplus for every dollar of spending), the fatality costs are nearly ten times greater.
These latter results are not fully explained in the working paper version, but the calculations seem relatively straightforward. A reasonable question is whether these results are simply correlations, or whether the sports games caused the increase in coronavirus cases and deaths. Wing et al. argue that their results are plausibly causal estimates:
Because NHL, NBA, and NCAA schedules were created prior to the outbreak, we can be condent that variation in home games due to scheduling was not influenced by local expectations about the state of the epidemic.
Since they limit their analysis to comparing counties (or MSAs) that have existing professional sports teams, and tend to be larger and more urban than counties without professional sports teams, their claim about causality is fair, although I would have liked to have seen some more robustness checks. For instance, they could have run a placebo test, using the number of scheduled home games for the 2019 or 2018 season within the same period. If the results are the same or similar, then the relationship between home sports games and coronavirus is either spurious, or driven by some other factor that their analysis fails to control for.
I'd expect some pushback from reviewers when this paper gets sent to peer review prior to journal publication, especially on the claims about causality. In terms of telling us about current sports events and their effects on coronavirus cases, the paper might be little help. As the authors note in their conclusion:
...our estimates are based on data generated from games played before social distancing policies and other adaptive behaviors were implemented. It is possible that sporting events would lead to less transmission if people were wearing masks and were seated in a socially distanced manner.
To the extent that social distancing is observed, the effects of more recent sporting events can be expected to be much lower.
[HT: Marginal Revolution]
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