They kept protesting that I was trying to have it both ways. But there are at least 5 or 6 other ways I am also trying to have it.
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Aug 31, 2021 • 13 tweets • 2 min read
If you are like me you have been dismayed at the recent news about waning vaccine efficacy. What used to be 95% protection is now measured to be much lower.
But these estimates are seriously confounded. A simple calculation shows the problem.
In the original randomized trials, efficacy was found to be about 95%. That is, the ratio of vaccinated cases to unvaccinated cases was 1/20.
Now we have only observational data. But using observational data can make that ratio look much larger even though it isn't.
Jun 25, 2021 • 16 tweets • 3 min read
The base-rate fallacy is about to become a daily nuisance when it comes to processing outbreak data in highly vaccinated societies. Here's a cautionary tale.
Today the Wall Street Journal has the following alarming news. In the recent surge of cases in Israel involving the Delta variant, half of all newly infected adults had been fully vaccinated. I almost cried when I read that.
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