The “shapiro.test” Function in R

• Package: stats (part of the base R installation)

• Purpose: To perform the Shapiro-Wilk test for normality.

• General Class: Statistical Testing

• Required Argument(s):

• x: A numeric vector containing the data to be tested for normality.

• Notable Optional Arguments:

• method: A character string indicating the method to be used. The default is "shapiro.test", which is the classical Shapiro-Wilk test. Other methods include "swilk" for Royston’s W test and "naive" for the Shapiro-Francia test.

• Example:

• # Example usage
  set.seed(123)
  my_data <- rnorm(100) # Generating a random normal sample
  
  # Performing the Shapiro-Wilk test
  result <- shapiro.test(my_data)
  
  # Displaying the test result
  print(result)

• In this example, shapiro.test is a function from the stats package that is used to assess whether a given numeric vector (x) comes from a normal distribution. The method argument is optional and allows you to choose different variants of the Shapiro-Wilk test. The result object contains the test statistic, p-value, and other information related to the test.