powertools (version 1.0.0)

anova2way.se.bal: Power calculation for test of simple effect for two-way balanced analysis of variance

Description

Conducts power and sample size calculations for a test of a simple effect in a two-way balanced (equal cell sizes) ANOVA. A "simple effect" is a contrast among the cell means. For a test of a contrast in an unbalanced (unequal cell sizes) two-way ANOVA, see anova2way.se.unbal. For a test of contrast among factor levels, see anova2way.c.bal.

Usage

anova2way.se.bal(
  n = NULL,
  mmatrix = NULL,
  cmatrix = NULL,
  sd = 1,
  Rsq = 0,
  ncov = 0,
  alpha = 0.05,
  power = NULL,
  sides = 2,
  v = FALSE
)

Value

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

Arguments

n

The sample size per cell.

mmatrix

A matrix of cell means (see example).

cmatrix

A matrix of contrast coefficients (see example).

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.

sides

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

v

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

Examples

mmatrix <- matrix(c(9.3, 8.9, 8.5, 8.7, 8.3, 7.3), nrow = 2, byrow = TRUE)
cmatrix <- matrix(c(-1, 0, 0, 1, 0, 0), nrow = 2, byrow = TRUE)
anova2way.se.bal(n = 30, mmatrix = mmatrix, cmatrix = cmatrix, sd = 2, alpha = 0.025, sides = 1)