Calculates conditional probability using Bayes' Theorem, updating probabilities based on new evidence.
Start with your values, or try a preset.
Enter Prior Probability of Event A (P(A)), Prior Probability of Not Event A (P(¬A)), Likelihood of Event B Given A (P(B|A)), and Likelihood of Event B Given Not A (P(B|¬A)) in the units shown.
Read Probability of Event B (P(B)) and Posterior Probability of A given B (P(A|B)) in the results panel. Results update as you change the inputs.
Choose a preset to load an example, then adjust the values for your situation.
See the inputs and their calculated results.
Prior Probability of Event A (P(A)): 0.1; Prior Probability of Not Event A (P(¬A)): 0.9; Likelihood of Event B Given A (P(B|A)): 0.8; Likelihood of Event B Given Not A (P(B|¬A)): 0.1
Probability of Event B (P(B)): 0.17; Posterior Probability of A given B (P(A|B)): 0.4705882353
Prior Probability of Event A (P(A)): 0.2; Prior Probability of Not Event A (P(¬A)): 0.8; Likelihood of Event B Given A (P(B|A)): 0.6; Likelihood of Event B Given Not A (P(B|¬A)): 0.3
Probability of Event B (P(B)): 0.36; Posterior Probability of A given B (P(A|B)): 0.3333333333
Prior Probability of Event A (P(A)): 0.5; Prior Probability of Not Event A (P(¬A)): 0.5; Likelihood of Event B Given A (P(B|A)): 0.9; Likelihood of Event B Given Not A (P(B|¬A)): 0.1
Probability of Event B (P(B)): 0.5; Posterior Probability of A given B (P(A|B)): 0.9
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