Definition
In statistics and machine learning, the base rate refers to the underlying frequency of a condition or outcome within a given dataset. Ignoring base rates often leads to the base rate fallacy, where predictions are biased toward specific evidence rather than general probabilities. Accurate models must account for class imbalance by considering these prior probabilities, especially in medical testing or fraud detection where positive cases are rare.
Summary
The base rate is the prior probability of an event occurring in a population, independent of any specific evidence or test results.
Key Concepts
- Prior probability
- Class imbalance
- Bayesian inference
- Base rate fallacy
Use Cases
- Medical diagnosis
- Fraud detection
- Risk assessment