The Number Needed to Treat (NNT) is the number of patients you need to treat to prevent one additional bad outcome (death, stroke, etc.). For example, if a drug has an NNT of 5, it means you have to treat 5 people with the drug to prevent one additional bad outcome.

"The ratio of the risk of an event in the experimental group compared to that of the control group (RR=EER / CER). Not to be confused with relative risk reduction." --CEBM Glossary

A statistic that quantifies the strength of association between "events" and "non-events". --CEBM Glossary

"The likelihood that a given test result would be expected in a patient with the target disorder compared to the likelihood that the same result would be expected in a patient without that disorder." --CEBM Glossary

"The range around a study’s result within which we would expect the true value to lie. CIs account for the sampling error between the study population and the wider population the study is supposed to represent." --CEBM Glossary

**Statistics Corner: Confidence Intervals**by Terry ShaneyfeltThis video describes the role and interpretation of confidence intervals.

Sensitivity is The proportion of people with disease who have a positive test. While Specificity, is the proportion of people free of a disease who have a negative test.

**Sensitivity and Specificity Explained Clearly**Understand sensitivity and specificity with this clear explanation by Dr. Roger Seheult of MedCram. Includes tips on remembering the differences between true positive, true negative, false positive, false negative, and other statistics, as well as the overall effect on clinical lab values.

- EBM Glossary - CEBMThe Centre for Evidence-Based Medicine glossary that outlines some of the key terms that should be understood in EBM/EBP.
- CEBM Oxford YouTube ChannelThis is the channel for the Centre for Evidence-Based Medicine at the University of Oxford.

- CATMaker and EBM Calculators - CEBMOn this page you can download CATmaker, the CEBM’s venerable computer-assisted critical appraisal software, and use our interactive EBM calculators.
- EBM CalculatorsCalculators created by the Knowledge Translation Program, Toronto.
- Diagnostic Test Calculator - Alan Schwartz, University of Illinois at ChicagoThis calculator can determine diagnostic test characteristics (sensitivity, specificity, likelihood ratios) and/or determine the post-test probability of disease given given the pre-test probability and test characteristics. Given sample sizes, confidence intervals are also computed.