AI engineering glossary · Evaluation metrics
What is prevalence?
Prevalence (also called base rate): The proportion of cases in a population that truly belong to the positive class. It strongly affects how a test's positive results should be interpreted, because even an accurate test produces mostly false alarms when the condition is very rare.
Prevalence: an example
If 20 of 1,000 transactions are fraudulent, prevalence is 2%.
Related terms
More Evaluation metrics terms
- Proper scoring rule
- R-precision
- Recall
- Recall at k
- Reciprocal rank
- Relevance judgments
- Reliability diagram
- Residual plot
Where you learn it
Prevalence is part of the AI Engineering Program, which teaches it with notes, a hands-on lab and an exam. The first lesson is free.