shapiro.test {stats} R Documentation

## Shapiro-Wilk Normality Test

### Description

Performs the Shapiro-Wilk test of normality.

### Usage

shapiro.test(x)


### Arguments

 x a numeric vector of data values. Missing values are allowed, but the number of non-missing values must be between 3 and 5000.

### Value

A list with class "htest" containing the following components:

 statistic the value of the Shapiro-Wilk statistic. p.value an approximate p-value for the test. This is said in Royston (1995) to be adequate for p.value < 0.1. method the character string "Shapiro-Wilk normality test". data.name a character string giving the name(s) of the data.

### Source

The algorithm used is a C translation of the Fortran code described in Royston (1995). The calculation of the p value is exact for n = 3, otherwise approximations are used, separately for 4 \le n \le 11 and n \ge 12.

### References

Patrick Royston (1982). An extension of Shapiro and Wilk's W test for normality to large samples. Applied Statistics, 31, 115–124. doi:10.2307/2347973.

Patrick Royston (1982). Algorithm AS 181: The W test for Normality. Applied Statistics, 31, 176–180. doi:10.2307/2347986.

Patrick Royston (1995). Remark AS R94: A remark on Algorithm AS 181: The W test for normality. Applied Statistics, 44, 547–551. doi:10.2307/2986146.

qqnorm for producing a normal quantile-quantile plot.
shapiro.test(rnorm(100, mean = 5, sd = 3))