Randomized trials often investigate changes from baseline as primary outcome variable. To design such studies, information on the distribution of such changes or on the correlation of baseline and follow-up values is needed and should be taken from previous studies. However, this information is often not transparently reported. In order to facilitate study design in such situations, we developed a webtool that simulates changes from baseline following a user-chosen assumption on the distribution or correlation. The webtool can also be used for sample size planning based on ANCOVA analysis.

Link to the web calculator.