*! version 1.0.0 07oct2019 Matteo Bottai

help m_power

m_power: Power and sample size to detect slope differences between two groups with mixed effects models

Syntax

m_power [, options]

Description

m_power estimates the detectable difference in the slope of a longitudinal linear trend between two groups using a random-intercept, random-slope mixed effect model (Yi and Panzarella, 2002).

Options

difference specifies the detectable difference; cannot be used if subjects is specified

subjects specifies the number of subjects; cannot be used if difference is specified

timepoints specifies the number of timepoints

level specifies the level of the test

power specifies the desired power

sigma specifies the residual scalar standard deviation

r specifies the residual correlation matrix in mata syntax

d specifies the random coefficient covariance matrix in mata syntax

Examples

m_power, subjects(100)

m_power, difference(1)

m_power, d(2,0\0,.5) sigma(1.5) subjects(200) power(.9)

Also see

[XT] mixed, [R] power

Reference

Yi Q. and Panzarella T (2002). Estimating sample size for tests on trends across repeated
measurements with missing data based on the interaction term in a mixed model. Controlled Clinical Trials 23: 481-496.

Author

Matteo Bottai

Unit of Biostatistics

Institute of Environmental Medicine, Karolinska Institutet

Stockholm, Sweden