COVID and the Mafia

Bayes’ Theorem may sound like a bit of irrelevant mathematics, but it explains a lot about racist behavior. Consider: All mafiosi are Sicilians, but most Sicilians are not mafiosi. Therefore, when you meet a Sicilian man you should not assume that he is in the mafia. He probably isn’t.

Now suppose that a cop observes that most of the criminals he encounters are Black. He might wrongly assume that every Black person he sees is likely to be a criminal. In fact, if 1% of all Blacks are criminals, then the chance that a particular Black person he sees is a criminal is still just 1%. The Blacks that he encounters might be a major part of the criminal population, but that does not mean that blacks in general are criminals.

The wikipedia article on Bayes’ Theorem. https://en.wikipedia.org/wiki/Bayes%27_theorem, has some excellent examples that also apply to COVID-19.