Interleukin-6 (IL-6) is a cytokine released as part of the immune response to an infection. Elevated IL-6 is suggested to be predictive of severe and even moderate illness among individuals infected with COVID-19. Suppose we wanted to conduct a study to see if this is true among patients with COVID-19 in South Carolina. Assuming from previous studies in other areas of the US, the mean IL-6 is 8.13 pg/mL (s.d.-5.98 pg/mL) among individuals with moderate disease and 7.66 pg/mL (s.d.-4.97 pg/mL) among individuals that are asymptomatic or have mild illness, how many people (in total) would we need to enroll in our new study to determine if there is a difference in means with 95% confidence and 90% power?