Sample size for a change-from-baseline continuous endpoint

Analysis of the change score (follow-up minus baseline). The change SD is \(\sigma\sqrt{2(1-\rho)}\); change-score analysis beats an unadjusted follow-up comparison only when \(\rho > 0.5\), and is never better than ANCOVA.

Usage

sampleSizeChangeScore(
  delta,
  sd,
  baseline_cor,
  power = 0.8,
  sig_level = 0.05,
  ratio = 1,
  sides = 2L,
  dropout = 0,
  cluster_size = NULL,
  icc = NULL
)

Arguments

delta, sd, baseline_cor, power, sig_level, ratio, sides, dropout, cluster_size, icc

As in sampleSizeANCOVA().

Value

A trial_power object.

See also

sampleSizeANCOVA()