Did Sturgis Really Cause 266,000 New COVID-19 Cases?

For indispensable reporting on the coronavirus crisis, the election, and more, subscribe to the Mother Jones Daily newsletter.A couple of days ago I linked to a study suggesting that the Sturgis Motorcycle Rally was responsible for 266,000 new cases of COVID-19 in August. Today the Wall Street Journal editorial page hit back with a piece called “The Sturgis Statistical Misfire.”
I was open to this for a couple of reasons. First, like a lot of COVID-19 research, this study was released quickly and without peer review. Second, the figure of 266,000 really did seem awfully high given the timeframe and the number of infections attributed to actual attendees. So even though I normally don’t waste my time with Journal editorials, this time I did.
It started off with some snark about “deplorables.” Then a bit of background. Then some more snark about “modelers,” although the study in question didn’t really rely on any sophisticated modeling. Then an irrelevant comparison to New York state, followed by the irrelevant observation that South Dakota is still a pretty low infection state. I was starting to wonder whether they’d ever get around to the actual statistical problem, when it finally showed up in the 8th paragraph. As you’ll recall, the study looked at COVID-19 case rates in counties with different rates of attendance at the rally and found that the higher the attendance, the higher the COVID-19 outbreak a week or two later. Here’s what the Journal has to say about that:
But many “high inflow” counties like Los Angeles, Maricopa (Arizona), Clark (Nevada) and El Paso were experiencing flare-ups before the rally. These counties may have shared other characteristics like higher population density that contributed to their increases. There could be other “endogenous” variables—for instance, counties with more people who attended the motorcycle rally may also have had populations less observant of social distancing.
That’s it. They cherry picked a few counties and suggested maybe their COVID-19 case rates would have gone up anyway. You can’t do that, of course: you have to look at every county, not just a few, to get any kind of valid measurement.
This is why I don’t waste time with Wall Street Journal editorials. It’s like reading the National Enquirer: big, brassy headlines but it’s all dross inside. I’m still open to the possibility that this study overestimated the effect of the Sturgis rally, but you’re going to have to do a lot better if you want to convince me. This is just culture war sniping—the Journal is very concerned that the study scolds the (mostly unmasked) Sturgis attendees while “liberals” give the (mostly masked) BLM protests a pass—not a serious response.
POSTSCRIPT: As I was writing this, I noticed that James Freeman’s column today is headlined “Did Trump Downplay Covid Enough?” Atta boy! Don’t just defend Trump from the liberal press jackals, go all in and claim that Trump’s only problem was not lying enough.

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