power.contrast.t: power function for contrasts

In mcfanda/cpower: Power analysis for contrasts

Description

computes power parameters for t-test associated with a custom contrast

Usage

power.contrast.t(cont = NULL, d = NULL, n = NULL, power = NULL,
  scale = "g", sig.level = 0.05, type = "between",
  alternative = c("two.sided", "one.sided"))

Arguments

cont	contrast codes as a numeric vector
d	effect size d
n	number of observations per cell
power	power of test (1 minus Type II error probability)
scale	used to scale the d index. It can be "g", "z" or a numeric value
sig.level	significance level (Type I error probability)
type	string specifying the type of t test. Can be abbreviated.
alternative	one- or two-sided test. Can be abbreviated

Details

Exactly one of the parameters 'd','n','power' and 'sig.level' must be passed as NULL, and that parameter is determined from the others.

The parameter scale controls the method used to scale the effect size d.

1. scale="g" assumes scaling by dividing 2*d by the sum of absolute coefficients

2. scale="z" assumes scaling by dividing d by the square-root of the sum of squares of the contrast weigths

3. numeric any constant that multiplies the unscaled d to obtain the scaled d

Value

Object of class '"power.htest"', a list of the arguments (including the computed one) augmented with 'method' and 'note' elements.

Author(s)

Marcello Gallucci, [e-mail]

mcfanda/cpower documentation built on May 28, 2019, 1 p.m.