powertools (version 1.0.0)

crt.xo.cont: Power for test of treatment effect in 2x2 crossover cluster randomized trial

Description

Power and sample size calculation for a 2x2 crossover cluster randomized trial. Can solve for power, number of clusters per arm (assumes equal number of cluster per arm), m, delta or alpha.

Usage

crt.xo.cont(
  m = NULL,
  J.arm = NULL,
  delta = NULL,
  sd = 1,
  icc = 0,
  icca = 0,
  iccb = NULL,
  cac = NULL,
  sac = 0,
  alpha = 0.05,
  power = NULL,
  sides = 2,
  v = FALSE
)

Value

A list of the arguments (including the computed one).

Arguments

m

The number of subjects measured during each cluster-period.

J.arm

The number of clusters in each arm.

delta

The difference between the intervention and control means under the alternative minus the difference under the null hypothesis.

sd

The total standard deviation of the outcome variable; defaults to 1.

icc

The within-cluster, within-period intraclass correlation coefficient; defaults to 0.

icca

The within-cluster, within-subject correlation (correlation between two measurements within the same subject); defaults to 0.

iccb

The within-cluster, between-period intraclass correlation coefficient. Either iccb OR cac must be specified.

cac

The cluster autocorrelation. Either iccb OR cac must be specified.

sac

The subject autocorrelation; defaults to 0.

alpha

The significance level or type 1 error rate; defaults to 0.05.

power

The specified level of power.

sides

Either 1 or 2 (default) to specify a one- or two- sided hypothesis test.

v

Either TRUE for verbose output or FALSE to output computed argument only.

Examples

crt.xo.cont(m = 30, J.arm = 4, delta = 0.3, icc = 0.05, cac = 0.8, sac = 0.4)
crt.xo.cont(m = 30, J.arm = 4, delta = 0.3, icc = 0.05, icca = 0.42, iccb = 0.04)
crt.xo.cont(m = 30, J.arm = 4, delta = 0.3, icc = 0.05, cac = 0.5)