center: Centering

In ILSAstats: Statistics for International Large-Scale Assessments (ILSA)

Centering

Description

Centers a vector, a matrix or a data frame to the grand mean or the group mean.

Usage

center(X, group = NULL, grandmean = NULL, groupmean = NULL, wt = NULL)

grand.mean(x, wt = NULL)

group.mean(x, group, wt = NULL)

getgroup.mean(x, group, wt = NULL)

Arguments

X	a matrix or a data frame.
group	a vector indicating the group for centering.
grandmean	a numeric or character vector indicating the number or the the names of columns of X to which grand-mean should be applied.
groupmean	a numeric or character vector indicating the number or the the names of columns of X to which group-mean should be applied.
wt	a numeric vector of weights.
x	a vector, a matrix or a data frame.

Value

a data frame, or a vector.

Examples

# Less data for shorter example
repdata2 <- repdata[1:10,c(1:3,6:10,51)]

### One variable ----

# grand-mean
grand.mean(repdata2$item01)
grand.mean(repdata2$item01,wt = repdata2$wt)

# group-mean
group.mean(repdata2$item01,group = repdata2$GROUP)
group.mean(repdata2$item01,group = repdata2$GROUP,wt = repdata2$wt)

### More than one variable with the same rule ----

# grand-mean
grand.mean(repdata2[,4:8])
grand.mean(repdata2[,4:8],wt = repdata2$wt)

# group-mean
group.mean(repdata2[,4:8],group = repdata2$GROUP)
group.mean(repdata2[,4:8],group = repdata2$GROUP,wt = repdata2$wt)

### More than one variable with different rules ----
center(repdata2, group = repdata2$GROUP, grandmean = 4:5, groupmean = 6:8, wt = repdata2$wt)
center(repdata2, group = repdata2$GROUP, grandmean = 6:8, groupmean = 4:5, wt = repdata2$wt)

center(repdata2, group = repdata2$GROUP, wt = repdata2$wt,
       grandmean = paste0("item0",1:3), groupmean = paste0("item0",4:5))
center(repdata2, group = repdata2$GROUP, wt = repdata2$wt,
       grandmean = paste0("item0",4:5), groupmean = paste0("item0",1:3))

ILSAstats documentation built on April 4, 2025, 12:05 a.m.