Current systems4 min read

Performance and benchmarks

Sensitivity, specificity and AUC — how AI is measured, and how to read the numbers in marketing materials.

Every AI system publishes performance numbers — but they only make sense if you understand the metrics. Sensitivity measures how often cancer is found; specificity measures how often healthy women are not sent for further tests; AUC summarises the balance across all thresholds.

Benchmarks only mean something in context: the tested population, disease prevalence, imaging equipment and task. A model that excels on 1.2 million mammograms from one country may behave differently elsewhere. Independent validation studies — not manufacturers' claims — are the numbers that count.

Metrics to understand

  • Sensitivity: cancers correctly detected
  • Specificity: healthy women correctly reassured
  • AUC: overall discrimination between cancer and no cancer
  • Calibration: do predicted risks match real outcomes

Compare like with like. An AI is only as good as the data it was validated on — look for independent studies relevant to the population.

In brief

Sensitivity and specificity tell two different halves of the story.
Independent studies count more than manufacturers' claims.
Performance can vary across populations and equipment.

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