The “describeBy” Function in R

• Package: psych

• Purpose: Summarizes data by a grouping variable.

• General class: Data summary

• Required argument(s):

• x: The data frame to be summarized.

• group: The grouping variable.

• Notable optional arguments:

• mat: Provide a matrix output rather than a list.

• digits: Number of digits to be reported when giving matrix output.

• Example:

• # Load the psych library
  library(psych)
  
  # Generate example data
  data <- data.frame(
  group = rep(c("Group A", "Group B"), each = 10),
  score = c(rnorm(10),rnorm(10,3,2))
  )
  
  # Summarize data by group using describeBy
  summary <- describeBy(data$score, data$group, mat = TRUE, digits = 2)
  print(summary)

• This example demonstrates how to use the describeBy function from the psych package to summarize data by a grouping variable. The function takes the grouping variable (group) and the data frame to be summarized (data) as required arguments. Optional arguments like mat and digits can be used to customize the output format.