Improperly reporting the presence of a condition when it’s not in reality. Example: HIV positive test when the patient is actually HIV negative
Improperly reporting the absence of a condition when in reality it’s the case. Example: not detecting a disease when the patient has this disease.
When false positives are more important than false negatives:
– In a non-contagious disease, where treatment delay doesn’t have any long-term consequences but the treatment itself is grueling
– HIV test: psychological impact
When false negatives are more important than false positives:
– If early treatment is important for good outcomes
– In quality control: a defective item passes through the cracks!
– Software testing: a test to catch a virus has failed
If you want to visually remember the definitions of precision and recall, check out this quora answer by Jason T Widjaja: https://www.quora.com/What-is-the-best-way-to-understand-the-terms-precision-and-recall/answer/Jason-T-Widjaja?srid=uWIN