center_grand_mean       Center with respect to grand mean
center_group_mean       Center with respect to group mean
center_mlm              Centering for multilevel analyses
composite_score         Composite column
dummy_coding            Dummy Coding
effect_coding           Effect Coding
listwise_deletion       Listwise deletion
mlbook_data             mlbook_data
recode_item             Recode values of a data frame
summarize_missing_values
                        Count the number of missing values
z_scored_grand_mean     Grand mean z-score
z_scored_group_mean     Z scored with with respect to the group mean
z_scored_mlm            Z-scored for multilevel analyses
z_scored_mlm_categorical
                        Z-scored for multilevel analyses
