How this calculation works
Changing the condition changes the reference group. P(A given B) and P(B given A) generally have different denominators.
THE FORMULA
P(A|B) = count(A∩B)/count(B)A worked example
12 of the 40 cases in B also meet A, giving 0.3.
Good to know
Each eligible case receives equal weight.
Reference: OpenStax Introductory Statistics (opens in a new tab) ↗
Read the result
Restrict the denominator to the cases that meet the condition.
The primary result is labeled “Probability of A given B”. Keep the input definitions in view when comparing this result with another method.
Try a related calculation
Each eligible case receives equal weight.
For a related exercise, try the statistics calculator.
A few questions, answered
How can I check the default inputs by hand?
12 of the 40 cases in B also meet A, giving 0.3.
Which rule does this calculator apply?
P(A|B) = count(A∩B)/count(B)