anova2way.c.bal: Power calculation for two-way balanced analysis of variance...

In powertools: Power and Sample Size Tools

Power calculation for two-way balanced analysis of variance contrast test

Description

Performs sample size and power calculations for a test of a contrast between levels of a factor in a two-way ANOVA with balanced data (that is, equal sized cells). Can be used to solve for power, n (sample size per cell), or alpha. For unbalanced data, see anova2way.c.unbal. For a test of a contrast among cell means, see anova2way.se.bal.

Usage

anova2way.c.bal(
  n = NULL,
  mmatrix = NULL,
  cvec = NULL,
  factor = c("a", "b"),
  sd = 1,
  Rsq = 0,
  ncov = 0,
  alpha = 0.05,
  power = NULL,
  v = FALSE
)

Arguments

n	The sample size per cell
mmatrix	A matrix of cell means (see example).
cvec	A vector of contrast coefficients c(c1, c2, ...).
factor	Either "a" for rows or "b" for columns depending on which factor the contrast test is being made on.
sd	The estimated standard deviation within each cell; defaults to 1.
Rsq	The estimated R^2 for regressing the outcome on the covariates; defaults to 0.
ncov	The number of covariates adjusted for in the model; defaults to 0.
alpha	The significance level (type 1 error rate); defaults to 0.05.
power	The specified level of power.
v	Either TRUE for verbose output or FALSE (default) to output computed argument only.

Value

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

Examples

mmatrix <- matrix(c(9.3, 8.9, 8.5, 8.7, 8.3, 7.3), nrow = 2, byrow = TRUE)
anova2way.c.bal(n = 30, mmatrix = mmatrix, cvec = c(1, 0, -1), factor = "b",
sd = 2, alpha = 0.05)

powertools documentation built on April 4, 2025, 5:02 a.m.