center: Center a data set based on a 'mp_data'

In mlmpower: Power Analysis and Data Simulation for Multilevel Models

Center a data set based on a mp_data

Description

Provides multilevel centering of a mp_data data set.

Usage

center(data, all = FALSE, ...)

Arguments

data	a mp_data or a list of mp_data.
all	a logical value to center all variables based on model defaults
...	see details below

Details

The ... needs to be the variable's name followed by equals and the centering strategy requested. There are three different strategies available:

• cwc = centering within cluster

• cgm = centering with group mean

• none = no centering

If all is set to TRUE then the default centering will be used unless overwritten by specifying a specific centering strategy.

Value

For ndata = 1 a single data.frame is returned. If a list of data sets are included then they will be contained in a list. Each data.frame has an additional center attribute which denotes the centering strategy used.

Examples

# Create Model
model <- (
    outcome('Y')
    + within_predictor('X')
    + effect_size(icc = 0.1)
)
# Set seed
set.seed(198723)

# Create data set with default centering
model |> generate(5, 50) |> center(all = TRUE) -> mydata

# Create data centering X with cwc
model |> generate(5, 50) |> center(X = cwc) -> mydata

# See centering strategy
attr(mydata, 'center')

mlmpower documentation built on June 8, 2025, 11:07 a.m.