TY - JOUR T1 - Catalogue of bias: attrition bias JF - BMJ Evidence-Based Medicine JO - BMJ EBM SP - 21 LP - 22 DO - 10.1136/ebmed-2017-110883 VL - 23 IS - 1 AU - David Nunan AU - Jeffrey Aronson AU - Clare Bankhead Y1 - 2018/02/01 UR - http://ebm.bmj.com/content/23/1/21.abstract N2 - ER -