Power and sample-size calculations for trials that compare slopes over time: Introducing the slopepower command.

ABSTRACT: Trials of interventions that aim to slow disease progression may analyze a continuous outcome by comparing its change over time-its slope-between the treated and the untreated group using a linear mixed model. To perform a sample-size calculation for such a trial, one must have estimates of the parameters that govern the between- and within-subject variability in the outcome, which are often unknown. The algebra needed for the sample-size calculation can also be complex for such trial designs. We have written a new user-friendly command, slopepower, that performs sample-size or power calculations for trials that compare slope outcomes. The package is based on linear mixed-model methodology, described for this setting by Frost, Kenward, and Fox (2008, Statistics in Medicine 27: 3717-3731).

SUBMITTER: Nash S 

PROVIDER: S-EPMC7614632 | biostudies-literature | 2021 Sep

REPOSITORIES: biostudies-literature