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 (1994). 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. The package also handles the categorical
time Mixed Model of Repeated Measures (MMRM) using the formula of Lu, Luo,
and Chen (2008)
Details
Package:
longpower
Type:
Package
Version:
1.0
Date:
2013-05-22
License:
GPL (>= 2)
LazyLoad:
yes
Author(s)
Michael C. Donohue <mdonohue@usc.edu> Anthony C. Gamst Steven D.
Edland
References
Diggle PJ, Heagerty PJ, Liang K, Zeger SL. (2002) Analysis
of longitudinal data. Second Edition. Oxford Statistical Science Series.
Liu, G., & Liang, K. Y. (1997). Sample size calculations for studies with
correlated observations. Biometrics, 53(3), 937-47.
Lu, K., Luo, X., & Chen, P.-Y. (2008). Sample size estimation for repeated
measures analysis in randomized clinical trials with missing data.
International Journal of Biostatistics, 4, (1)