Sample Size Calculations for Longitudinal Data

Compute power and sample size for linear models of longitudinal data. Supported models include mixed-effects models and models fit by generalized least squares and generalized estimating equations. Relevant formulas are derived by Liu and Liang (1997) , Diggle et al (2002) , and Lu, Luo, and Chen (2008) .


The longpower package contains functions for computing power and sample size for linear models of longitudinal data based on the formula due to Liu and Liang (1997) and Diggle et al (2002). Either formula is expressed in terms of marginal model or Generalized Estimating Equations (GEE) parameters. This package contains functions which translate pilot mixed effect model parameters (e.g. random intercept and/or slope) into marginal model parameters so that the formulas of Diggle et al or Liu and Liang formula can be applied to produce sample size calculations for two sample longitudinal designs assuming known variance.

install.packages("longpower")

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install.packages("longpower")

1.0-19 by Michael C. Donohue, 14 days ago


https://github.com/mcdonohue/longpower


Browse source code at https://github.com/cran/longpower


Authors: Michael C. Donohue


Documentation:   PDF Manual  


Task views:


GPL (>= 2) license


Depends on lme4, nlme

Suggests knitr, gee, testthat, methods


See at CRAN