Denham, James W.Lamb, David S.Joseph, DavidMatthews, JohnAtkinson, ChrisSpry, Nigel A.Duchesne, GillianEbert, MartinSteigler, AllisonD'Este, Catherine2025-02-102025-02-100167-8140https://hdl.handle.net/1885/733735163Dear Sir We write to draw readers’ attention to a little recognised form of bias that can influence conclusions which are drawn from the study of patient treatment response subgroups derived after the treatment results become known [1]. We use some of our own data to illustrate the issue.application/pdfen-AU©2011 The authorscancer growthcancer mortalityclinical effectiveness;humanillness trajectoryprostate cancer201110.1016/j.radonc.2011.08.0322024-01-07