The obscure maths theorem that governs the reliability of Covid testing

There’s been much debate about lateral flow tests – their accuracy depends on context and the theories of a 18th-century cleric

**Hasnain says:**

This is a generally decent article except for one really fatal flaw - could they have not asked anyone who’s ever taken an introductory stats course about Bayes’ theorem? I would hope they’d immediately learn it wasn’t that obscure.

“It’s not. And that’s because of a fascinating little mathematical anomaly known as Bayes’s theorem, named after the Rev Thomas Bayes, an 18th-century clergyman and maths nerd.

Bayes’s theorem is written, in mathematical notation, as P(A|B) = (P(B|A)P(A))/P(B). It looks complicated. But you don’t need to worry about what all those symbols mean: it’s fairly easy to understand when you think of an example.”