S chart showing sustained reduction in length of stay (LOS) for all inpatients and a reduction in the variation around the mean length of stay. S chart showing sustained reduction in length of stay (LOS) for all inpatients and a reduction in the variation around the mean length of stay. CL, centre line; UCL, upper control line; LCL, lower control line. Emma Donaldson et al. Frontline Gastroenterol 2015;6:182-193 Copyright © BMJ Publishing Group Ltd & British Society of Gastroenterology. All rights reserved.