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Physical distancing interventions and incidence of coronavirus disease 2019: natural experiment in 149 countries

BMJ 2020; 370 doi: (Published 15 July 2020) Cite this as: BMJ 2020;370:m2743

Linked Editorial

Lockdown-type measures look effective against covid-19

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Rapid Response:

concern about fitted model

Dear Editor,

I am concerned that the model does not fit the data and also that the jumps in the fitted model do not make sense, considering the blurring in the underlying process. I was alerted to this by someone who pointed out the graph for Canada on page 84 of the supplementary material. The disconnect between the fit and the data gives me skepticism about the larger claims in the article.

I also have concerns about the data, similar to those raised by the peer reviewers regarding selection effects in who gets tested.

Competing interests: No competing interests

20 July 2020
Andrew Gelman
Columbia University
Department of Statistics, Columbia University