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EBM Tools

Finding the evidence: a how-to guide

1 - Using PICO to formulate a search question. 2 - Turning search terms into a search strategy. 3 - Turning your search strategy into results (searching pubmed).

Critical Appraisal tools

Critical appraisal worksheets to help you appraise the reliability, importance and applicability of clinical evidence.

Number Needed to Treat (NNT)

The Number Needed to Treat (NNT) is the number of patients you need to treat to prevent one additional bad outcome (death, stroke, etc.).

Likelihood Ratios

The Likelihood Ratio (LR) is the likelihood that a given test result would be expected in a patient with the target disorder compared to the likelihood that that same result would be expected in a patient without the target disorder.


Put the “like” into your likelihood ratios with the CEBM’s CATmaker.

Study designs

This short article gives a brief guide to the different study types and a comparison of the advantages and disadvantages.

Levels of evidence

Levels of Evidence: An introduction

This must be read before using the Levels: no evidence ranking system or decision tool can be used without a healthy dose of judgement and thought.