CATMaker and EBM Calculators

On this page you can download CATmaker, the CEBM’s venerable computer-assisted critical appraisal software, and use our interactive EBM calculators.

Please note that you will need the Shockwave plug-in to view the calculators. If you do not have Shockwave installed, you will be presented with the opportunity to download it. We recommend you do so, as this adds functionality to your browser.

CATmaker

CATmaker is a computer-assisted critical appraisal tool, which helps you create Critically Appraised Topics (CATs), for the key articles you encounter about Therapy, Diagnosis, Prognosis, Aetiology/Harm and Systematic Reviews of Therapy.

Download CATmaker (3MB, PC format only) – the full version

All-purpose 2×2 table EBM calculator

  1. Type the appropriate numbers in the white boxes (you can TAB between boxes to save using the mouse);
  2. Click (or un-click) the sets of calculations you want to do (Rx for therapy, Dx for diagnosis and H for harm/aetiology);
  3. Click CALC;
  4. Click CLEAR to, er, clear the values and start again

Diagnostic calculator and visualiser

This 2×2 table works out your sensitivities, specificities and likelihood ratios.  Not content with that, it also gives you a lovely visualisation of the overall accuracy of your test.

  1. Type the appropriate numbers in the boxes (you can TAB between boxes to save using the mouse);
  2. Click CALC;
  3. Click CLEAR to, er, clear the values and start again.

Interactive nomogram

Drag the blue arrows to the values you have for your patient’s pre-test probability (%) and the test result’s LR, and read off the post test probability from the red arrow on the right.