Talking about Conditional Probabilities

First, let’s review on how to talk about different conditional probabilities.

P(A) = “probability of A”
Ex. Probability of flipping “heads” with a coin

P(A∧B) = P(A)*P(B) = “probability of A and B”
Ex. Probability of getting “heads” twice in a row (independent)
Ex. Probability of having an elevated troponin and an acute MI (dependent)

P(A|B) = “probability of A given B”
Ex. Probability of an MI given an elevated troponin (hint: PPV)
Ex. Probability of no MI given a normal troponin (hint: NPV)

• Talking about Conditional Probabilities
• Fundamentals
• Positive and Negative Predictive Value
• Sensitivity and Specificity
• Example: Positive Predictive Value
• Spectrum bias
• Bayes’ Theorem
• Example: Using Likelihood Ratios