Episode 9 of CRAMSURG - Clinical Reasearch Appraisal and Methodology for Surgical Trainees. The paper for discussion is Laparoscopic versus open colorectal surgery in the acute setting (LaCeS trial): a multicentre randomized feasibility trial, BJS Jun 2020 The teaching topic is bias in observational studies. Brought to you by CRAMSURG www.cramsurg.org.