Elevated alanine aminotransferase (ALT), a liver enzyme, is an indicator of severe illness among individuals infected with COVID-19. Suppose we wanted to conduct a study to compare the mean ALT concentration (U/L) between a sample of adult patients hospitalized at MUSC for COVID-19 infection (X =22.0, s=15.8) to the mean ALT concentration (U/L) of healthy U.S. adults (H=19.0, o=11.9). How many patients would we need to enroll from MUSC to conduct this study with 99% confidence, and 80% power? From: Chen T, Wu D, Chen H, et al. Clinical characteristics of 113 deceased patients with coronavirus disease 2019: retrospective study [published correction appears in BMJ. 2020 Mar 31;368:m1295]. BMJ. 2020;368:m1091. Published 2020 Mar 26. doi:10. 1136/bmj_m1091 O 184 O 104 216 O 204