Fill in the four parts and this writes the question your supervisor is asking for — and the PubMed search that goes with it.
Clinical research tools
Free calculators for the arithmetic that comes up in clinical projects: framing an answerable question, sizing an audit, reading a diagnostic test, turning a trial result into a number a patient can use, and telling improvement from noise. Everything runs in your browser. Nothing is uploaded and nothing asks for an email.
Enter the four counts and this returns every diagnostic accuracy measure with confidence intervals — and shows why PPV changes when prevalence does.
Enter the events in each arm and this returns absolute and relative risk reduction, the number needed to treat, and why the two look so different.
Audit sample size is not a power calculation. This works out how many records give you a compliance figure precise enough to act on.
Paste your numbers in order. This draws the run chart and applies the four rules that distinguish a real change from ordinary variation.