I was bored during lockdown, so I decided to start a blog about my random thoughts about math. It contains some solutions to math problems, and some 'simple' applications of math.
Saturday, 27 November 2021
Corona tests vs symptoms
corona
Who is more likely to have covid? Someone who has a negative selftest,
but has cold-like symptoms, or someone with a positive test but who
has no symptoms?
Define the following:
C: patient has convid
T: patient tested positive
S: patient is symptomatic
We use the following data from the following sources
If A and B are independant under constant X that P(X∣A∧B)=P(X∧A∧B)/P(A∧B)=P(A∧B∣X)P(X)/P(A∧B)=P(A∣X)P(B∣X)P(X)/P(A∧B)=P(A∧X)P(B∧X)/P(A∧B)P(X)=P(A∧X)P(B∧X)/(P(A∧B∧X)+P(A∧B∧Xˉ))P(X)=P(A∧X)P(B∧X)/(P(A∧B∣X)P(X)+P(A∧B∣Xˉ)P(Xˉ))P(Xˉ)=P(A∧X)P(B∧X)/(P(A∣X)P(B∣X)P(X)+P(A∣Xˉ)P(B∣Xˉ)P(Xˉ))P(X)=P(A∣X)P(B∣X)P(X)/(P(A∣X)P(B∣X)P(X)+P(A∣Xˉ)P(B∣Xˉ)P(Xˉ))=1+P(A∣X)P(B∣X)P(X)P(A∣Xˉ)P(B∣Xˉ)P(Xˉ)1