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WSTATISTIC procedure

Calculates the Shapiro-Wilk test for Normality (R.W. Payne).

Option

PRINT = string tokens What to print (test); default test

Parameters

DATA = variates Samples of data to be tested for Normality
W = scalars Saves the Shapiro-Wilk W statistic for each sample
PROBABILITY = scalars Saves the probability for W under the assumption that the data are Normal

Description

WSTATISTIC uses the Shapiro-Wilk test to assess whether a sample of data comes from a Normal distribution. The data values must be supplied, in a variate, using the DATA parameter. By default WSTATISTIC prints the statistic, W, with its probability value under the assumption that the data are Normal. (So a low probability indicates that the data are unlikely to be from a Normal distribution.) The printed output can be supressed by setting option PRINT=*. The test statistic can be saved, in a scalar, using the W parameter, and its probability can similarly be saved using the PROBABILITY parameter.

Option: PRINT.

Parameters: DATA, W, PROBABILITY.

Method

WSTATISTIC calculates the statistic and its probability using the methods of Royston (1993, 1995).

Action with RESTRICT

The DATA variate can be restricted to assess a subset of the data.

References

Royston, P. (1993). A toolkit for testing for non-normality in complete and censored samples. The Statistician, 42, 37-43.

Royston, P. (1995). A remark on Algorithm AS 181: the W-test for Normality. Applied Statistics, 44, 547-551.

See also

Directive: DISTRIBUTION.

Procedures: EDFTEST, NORMTEST.

Commands for: Basic and nonparametric statistics.

Example

CAPTION    'WSTATISTIC example','Data from Royston (1995)'; STYLE=meta,plain
VARIATE    [VALUES=4.2,4.9,5.2,5.3,6.7,6.7,7.2,7.5,8.1,8.6,8.8,9.3,\
           9.5,10.3,10.8,11.1,12.2,12.5,13.3,15.1,15.3,16.1,19.0,19.5] Glucose
WSTATISTIC Glucose
Updated on March 4, 2019

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