Performs power calculations for an lme object

This is a method for the Pwr generic function. It works for the example given in Galecki and Burzykowski (2013) but may require additional testing, especially for post-hoc power analysis.

# S3 method for class 'lme'
Pwr(
  object,
  ...,
  type = c("sequential", "marginal"),
  Terms,
  L,
  verbose = FALSE,
  ddf = numeric(0),
  alpha = 0.05,
  altB = NULL,
  tol = 1e-10
)

Arguments

object

an lme object containing a model fit, which provides information needed for power calculations.

...

some additional arguments may be required.

type

an optional character string specifying the type of sum of squares to be used in F-tests needed for power calculations. Syntax is the same as for anova.lme in the nlme package.

Terms

an optional integer or character vector specifying which terms in the model should be jointly tested to be zero using a Wald F-test. See anova.lme in the nlme package for details.

L

an optional numeric vector or array specifying linear combinations of the coefficients in the model that should be tested to be zero. See anova.lme in the nlme package for details.

verbose

logical. If TRUE, additional information is provided. See anova.lme in the nlme package for details.

ddf

numeric scalar value. Redefines the default number of denominator degrees of freedom.

alpha

numeric scalar value. By default, 0.05.

altB

matrix or vector containing alternative values for beta parameters.

tol

numeric scalar value for numerical tolerance.

Value

A data frame inheriting from class Pwr.lme.

References

Galecki, A., & Burzykowski, T. (2013). *Linear Mixed-Effects Models: A Step-by-Step Approach*. Springer.

See also

anova.lme

Author

Andrzej Galecki and Tomasz Burzykowski