Programming the statistical procedures from SAS

How to test if a sample has a Normal Distribution?

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Occasional Contributor
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How to test if a sample has a Normal Distribution?


Hi,

I have a small Sample (with 30 points/observations) as variable "Sample" inside a Data Set named 'Data'.

I would like to know how to test if the this sample has a Normal Distribution.

Thanks!


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‎07-26-2013 11:35 AM
Valued Guide
Posts: 2,108

Re: How to test if a sample has a Normal Distribution?

PROC UNIVARIATE has multiple tests for normality.  None of the tests are very powerful, so I'll also look at the plots for an eyeball test.

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‎07-26-2013 11:35 AM
Valued Guide
Posts: 2,108

Re: How to test if a sample has a Normal Distribution?

PROC UNIVARIATE has multiple tests for normality.  None of the tests are very powerful, so I'll also look at the plots for an eyeball test.

Respected Advisor
Posts: 2,655

Re: How to test if a sample has a Normal Distribution?

And if the sample size is large (N>100) the tests are over-powered, where even small deviations can lead to a significant result.

Follow Doc's advice and look at the plots, especially the pp and qq plots.

Steve Denham

SAS Super FREQ
Posts: 3,306

Re: How to test if a sample has a Normal Distribution?

This should get you started:

ods graphics on;

PROC UNIVARIATE DATA=sashelp.iris(where=(Species="Virginica"));

VAR SepalLength;

histogram SepalLength / Normal;

qqplot SepalLength / Normal;

RUN;

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