Exercise

Sample size for unequal groups

Here we will calculate the sample size required for a trial where patients will be randomized to active treatment and placebo in a 2:1 ratio for a two-sided t-test. The samplesize library has been loaded for this session.

Instructions

100 XP

Use the n.ttest() function within the samplesize package to calculate the sample size for a trial with an expected treatment difference of 1.5, common standard deviation of 2.5, 90% power, and a 2:1 ratio.