zscore.by.group: z-Score Within Each of Several Cells

In sfraundorf/psycholing: R Functions for Common Psycholingusitic and Cognitive Designs

z-Score Within Each of Several Cells

Description

z-scores x within each of one or more cells. For instance, z-score Likert scale ratings within each participant, or z-score response times within each participant x condition pairing.

Usage

zscore.by.group(x, INDEX)

Arguments

x	a numeric vector
INDEX	list of one or more grouping variables, typically factors, each of the same length as x

Value

numeric vector with x z-scored separately within each level of INDEX

See Also

center.by.group to center within groups without scaling by the standard deviation.

Examples

my.data <- data.frame(Subject=c(rep('S1',6), rep('S2',6)),
                      Session=c(rep('Day1',3), rep('Day2',3),
                                rep('Day1',3), rep('Day2',3)),
                      Rating=c(10,30,20,20,40,30,15,35,25,25,45,35))
# z-score within each subject:
my.data$Rating.Subject.z <- zscore.by.group(my.data$Rating, my.data$Subject)
# z-score within each subject x session pairing:
my.data$Rating.SubjectSession.z <- zscore.by.group(my.data$Rating,
list(my.data$Subject, my.data$Session))

sfraundorf/psycholing documentation built on April 23, 2022, 2:50 a.m.