This web-based app helps you to evaluate screening tool by calculating various diagnostic efficiency statistics.
The four cells (a, b, c, d) capture the four possible relationships between the results of a screening test and a gold standard diagnosis.
True positive (cell a): when the person scores positive on the screening test and does in fact have the condition. False positive (cell b): when the person scores positive on the screening test but does not in fact have the condition. False negative (cell c): when the person scores negative on the screening test but does in fact have the condition. True negative (cell d): when the person scores negative on the screening test and does not in fact have the condition.