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Evidence-Based Resources: EBM Calculations Explained

Number Needed to Treat (NNT)

NNT Tutorial by Graham Walker. Video  (4 min)

How to calculate the number needed to treat by Terry Shaneyfelt.  Video (3 min.)

Number needed to treat by Phillip Sedgewick. BMJ 2010; 341:c5614

Absolute Risk Reduction (ARR), Relative Risk Reduction (RRR), Relative Risk (RR)

How to calculate relative risk. Terry Shaneyfelt. Video (3 min.)

Odds Ratios

Understanding Odds Ratios. Gordon Guyatt, MD. Video (21 min.)

How to Calculate an Odds Ratio. Terry Shaneyfelt. Video (3 min.)

Odds ratios. Philip Sedgewick. BMJ 2010;341, 2010.

Forest Plots

How to Interpret a Forest Plot. Terry Shaneyfelt. Video (5 min.)

Interpreting and understanding meta-analysis graphs -- a practical guide.  Aust Fam Physician 2006 Aug; 35(8):635-8. PMID 1689442.

Confidence Intervals

Confidence Intervals.  Terry Shaneyfelt. Video (5 min.)

Other Stats and Resources

EBM Calculators

EBM Calculators from the Centre for Evidence-Based Medicine, Toronto

EBM and Decision Tools by Alan Schwartz (Diagnostic Test Calculator and NNT/NNH Calculator)