
WILKS SHAPIRO NORMALITY TESTName:
where the summation is from 1 to n and n is the number of observations. The array X contains the original data, X' are the ordered data, \( \bar{X} \) is the sample mean of the data, and w'=(w_{1}, w_{2}, ... , w_{n}) or
M denotes the expected values of standard normal order statistics for a sample of size n and V is the corresponding covariance matrix. W may be thought of as the squared correlation coefficient between the ordered sample values (X') and the w_{i}. The w_{i} are approximately proportional to the normal scores M_{i}. W is a measure of the straightness of the normal probability plot, and small values indicate departures from normality. Note that the Dataplot PPCC PLOT command is based on a similar concept. Monte Carlo simulations studies have indicated that the WilksShapiro test has good power properties for a wide range of alternative distributions.
<SUBSET/EXCEPT/FOR qualification> where <y> is the response variable being tested; and where the <SUBSET/EXCEPT/FOR qualification> is optional.
WILKS SHAPIRO NORMALITY TEST Y1 SUBSET TAG > 2
LET A = WILK SHAPIRO TEST PVALUE Y In addition to the above LET command, builtin statistics are supported for about 20+ different commands (enter HELP STATISTICS for details).
WILKS SHAPIRO Y
SKIP 25 READ ZARR13.DAT Y SET WRITE DECIMALS 5 WILKS SHAPIRO NORMALITY TEST YThe following outpout is generated: WilkShapiro Test for Normality Response Variable: Y H0: The Data Are Normally Distributed Ha: The Data Are Not Normally Distributed Summary Statistics: Total Number of Observations: 195 Sample Mean: 9.26146 Sample Standard Deviation: 0.02279 Sample Minimum: 9.19685 Sample Maximum: 9.32797 Test Statistic Value: 0.99827 PValue: 0.99923 Conclusions  Null Hypothesis Null Null Confidence Acceptance Hypothesis Hypothesis Level Interval Conclusion  Normal 50.0% (0.500,1) ACCEPT Normal 80.0% (0.200,1) ACCEPT Normal 90.0% (0.100,1) ACCEPT Normal 95.0% (0.050,1) ACCEPT Normal 97.5% (0.025,1) ACCEPT Normal 99.0% (0.010,1) ACCEPT Normal 99.9% (0.001,1) ACCEPT  
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Date created: 6/5/2001 