RT Journal Article SR Electronic T1 Tips for learners of evidence-based medicine: 1. Relative risk reduction, absolute risk reduction and number needed to treat JF Canadian Medical Association Journal JO CMAJ FD Canadian Medical Association SP 353 OP 358 DO 10.1503/cmaj.1021197 VO 171 IS 4 A1 Alexandra Barratt A1 Peter C. Wyer A1 Rose Hatala A1 Thomas McGinn A1 Antonio L. Dans A1 Sheri Keitz A1 Virginia Moyer A1 Gordon Guyatt for A1 The Evidence-Based Medicine Teaching Tips Working Group YR 2004 UL http://www.cmaj.ca/content/171/4/353.abstract AB