Diagnostic accuracy
Enter your screening or diagnostic test name, the reference standard (true disease status), and the four cell counts. All measures update instantly.
Test and disease
Context
Observed counts
| Disease + | Disease − | Total | |
|---|---|---|---|
| Test + | 95 | ||
| Test − | 205 | ||
| Total | 100 | 200 | 300 |
a = true positive · b = false positive · c = false negative · d = true negative
Accuracy measures
Predictive values
PPV and NPV below are sample-based — they reflect the disease prevalence in your study sample. In practice, predictive values change with population prevalence. Use the Predictive values tool to adjust sensitivity and specificity to any prevalence.
Hypothesis tests