summarySEwithin: Calculate Within-Subjects Summary Statistics with Error Bars

In ccamp83/mu: R package for general statistical analysis of univariate and multivariate data

Calculate Within-Subjects Summary Statistics with Error Bars

Description

A collection of functions for calculating summary statistics and error bars for within-subjects designs, implementing the method described in Morey (2008). This is particularly useful for creating plots with appropriate error bars for within-subjects variables in ggplot2.

Usage

summarySEwithin(
  data = NULL,
  measurevar,
  betweenvars = NULL,
  withinvars = NULL,
  idvar = NULL,
  na.rm = FALSE,
  conf.interval = 0.95,
  .drop = TRUE
)

Arguments

data	A data frame containing the variables
measurevar	The name of the measure variable
betweenvars	A vector containing names of between-subjects variables
withinvars	A vector containing names of within-subjects variables
idvar	The name of the variable that identifies subjects
na.rm	Should NA values be removed? (default = FALSE)
conf.interval	Confidence interval level (default = 0.95)
.drop	Should unused factor levels be dropped? (default = TRUE)

Details

This implementation follows Morey's (2008) correction for within-subjects designs. It automatically:

• Converts non-factor variables to factors

• Normalizes the data within subjects

• Applies the Morey correction factor

• Combines normed and un-normed results

Value

A data frame containing:

• N: number of subjects

• Original measurevar: raw means

• sd: standard deviation

• se: standard error

• ci: confidence interval

Main Functions

• summarySEwithin: Calculates within-subjects summary statistics

• summarySE: Calculates basic summary statistics

• normDataWithin: Normalizes data for within-subjects variables

Source

http://www.cookbook-r.com/Graphs/Plotting_means_and_error_bars_(ggplot2)/#understanding-within-subjects-error-bars

References

Morey, R. D. (2008). Confidence intervals from normalized data: A correction to Cousineau (2005). Tutorial in Quantitative Methods for Psychology, 4(2), 61-64.

Examples

# Example with one between-subjects and one within-subjects variable
summarySEwithin(data = mydata,
               measurevar = "score",
               betweenvars = "group",
               withinvars = "time",
               idvar = "subject")

ccamp83/mu documentation built on Nov. 7, 2024, 5:17 p.m.