This function will group mean centered the scores at the level 1 and create an aggregated mean score for each group at L2.
After that, the group-mean-centered L1 scores and mean L2 scores will be z-scored with respect to the grand mean.
Please see `center_mlm` if you want to use the version without the z-scoring.
An object of the same type as .data. The output has the following properties:
1. Columns from .data will be preserved
2. Columns with L1 scores that are group-mean centered then grand-mean z-scored.
3. Columns with L2 aggregated means that are z-scored
Arguments
data
A data.frame or a data.frame extension (e.g. a tibble).
cols
Columns that need to be centered. See `dplyr::dplyr_tidy_select` for available options.
group
The grouping/cluster variable.
keep_original
default is `TRUE`. Set to `FALSE` to remove original columns