A test of the null hypothesis that a sample has been drawn from a normal distribution. An attractively simple test is that proposed by the Irish statistician Roy Geary in 1935. The Geary test compares the ratio of the mean deviation (see mean absolute deviation) divided by the standard deviation with the theoretical ratio for a normal distribution, which is . An alternative is the D'Agostino test suggested by D’Agostino in 1971. With ordered observations x(1)≤x(2)≤⋯≤x(n), the test statistic (see hypothesis test) is D, given by
where x¯ is the sample mean. Special tables are required.Several more general tests of specified distributions have special cases for testing for normality. Examples include the Anderson–Darling test and the Shapiro–Wilk test. See also Cramér–von Mises test; Kolmogorov–Smirnov test.
- variance
- variance, analysis of
- variance components model
- variance-ratio test
- variance reduction techniques
- variance–covariance matrix
- variant field
- variate
- variation
- variational method
- variational principle
- variation of latitude
- variegated capitalism
- variegation
- varies directly
- variety
- varimax rotation
- variogram
- variolitic
- variometer
- varistor
- Varmus, Harold Eliot
- Microsoft
- microsome
- microspar