So, let's look at the errors. The paper is here:https://onlinelibrary.wiley.com/doi/abs/10.1111/ijcp.13528 …
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Basically, the authors did two things: 1) calculated the average growth rate in cases of COVID-19, and for some reason called this average R(ADIR) 2) used linear regression to predict R(ADIR) using a few oddly-chosen variables
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They found that the only thing that significantly* predicted R(ADIR) was cases/1,000 of COVID-19, and then extrapolated from the regression equation to assume that if cases/1,000 = 6.6 the R(ADIR) would be 0 *STATISTICALLYpic.twitter.com/qwxzjNENcq
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This is the FIRST big mistake You can't just assume linearity, and you certainly can't just extrapolate like that. For example, marathon times have been going down for years, but if we extrapolate linearly to the year 2100 they'll take 0 minutes to run!
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You can run statistical tests to check all of these things and see if your assumptions are correct, but the authors didn't This is first-year stats stuff, and it's just missed entirely
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Which brings us to the SECOND big mistake: collinearity Without delving into too much depth, it's bad statistical practice to regress two things that we know are very closely relatedpic.twitter.com/GibiB0Hffl
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In this case, the authors calculated a variable (R(ADIR)) from new case numbers, and then regressed it against case numbers THESE TWO VARIABLES WILL ALWAYS BE CORRELATED BECAUSE THEY ARE CALCULATED FROM THE SAME INFORMATION
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It's like regressing your age in years against the average age you've been over the last decade, and then shouting "Eureka!" when you find they are closely tied Again, a simple mistake, and something a first-year stats student is taught not to do
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The THIRD big mistake is epidemiological. The authors assumed - with no evidence whatsoever - that an R(ADIR) of 0 meant immunity This is WRONGpic.twitter.com/2eCmbzdVDH
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Replying to @GidMK
This seems to be wrong from two perspectives. Not only is it wrong to assume that R(ADIR) = 0 means that all untested people have been exposed & are immune, it also assumes that exposure & recovery results in ongoing immunity. Is there evidence yet that people become immune?
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From my understanding, there is sufficient evidence for some immunity, but how long this will last and how protective it is is not certain
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Replying to @GidMK
I guess it's to be expected that there would be a certain level of immunity... but to assume complete immunity (especially given the recommendation for reduced isolation & subsequent coverage by media) seems risky
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