Bayesian Reasoning: Librarians and Farmers

This visualization demonstrates Bayes' theorem using the classic example from 3Blue1Brown about inferring whether someone is a librarian or a farmer based on whether they are shy. Drag the dividers to adjust probabilities.

What % of people are librarians?: 30.0%
What % of librarians are shy?: 70.0%
What % of population are shy librarians?
21.0%
What % of population are shy farmers?:
14.0%
What % of farmers are shy?: 20.0%

Marginal/Evidence, P(E)

What % of population are shy?

35.0%

Calculated as...

21.0%
+
14.0%

Posterior, P(H|E)

What % of shy people are librarians?

60.0%

Calculated as...

21.0%
21.0%
+
14.0%

Inspired by 3Blue1Brown's video on Bayes' theorem. Drag the dividing lines to adjust probabilities and see how they affect the results.