On immunity passports, Bayesian statistics, and why a "95% accurate" test saying you've had Covid-19 does not mean that there's a 95% chance you've had Covid-19

(I think this is quite an important point that doesn't seem to have been addressed much?) https://unherd.com/2020/04/how-far-away-are-immunity-passports/

with thanks to @kjm2 for statistical sense-checks

I'm going to tweet this one a few times because I worry that it's quite hard to make Bayesian statistics sound exciting, but it's genuinely easy to understand and really important. This question is key – and for the record, most doctors get it wrong: https://unherd.com/2020/04/how-far-away-are-immunity-passports/