PROC NPAR1WAY Example: Exact Wilcoxon Test

This script creates a 'React' dataset containing reaction times for two stimulus groups. It then executes the NPAR1WAY procedure to perform a Wilcoxon-Mann-Whitney test. The 'correct=no' option suppresses the continuity correction, and the 'exact wilcoxon' statement requests the exact p-value calculation, which is relevant for small samples.

Data Analysis

Type : INTERNAL_CREATION

Data is generated via the DATALINES statement in the DATA step 'React'.

1 Code Block

DATA STEP Data

Explanation :
Creation of the 'React' dataset. The 'input' statement uses ' @@' (double trailing at) to read multiple observations per data line, thus correcting the artifact present in the provided source code.

Copied!

1	DATA React;
2	INPUT Stim Time @@;
3	DATALINES;
4	1 1.94 1 1.94 1 2.92 1 2.92 1 2.92 1 2.92 1 3.27
5	1 3.27 1 3.27 1 3.27 1 3.70 1 3.70 1 3.74
6	2 3.27 2 3.27 2 3.27 2 3.70 2 3.70 2 3.74
7	;

2 Code Block

PROC NPAR1WAY

Explanation :
Execution of the non-parametric analysis. 'wilcoxon' requests the rank test. 'exact wilcoxon' calculates the exact significance.

Copied!

1	PROC NPAR1WAY wilcoxon correct=no DATA=React;
2	class Stim;
3	var Time;
4	exact wilcoxon;
5	RUN;

This material is provided "as is" by We Are Cas. There are no warranties, expressed or implied, as to merchantability or fitness for a particular purpose regarding the materials or code contained herein. We Are Cas is not responsible for errors in this material as it now exists or will exist, nor does We Are Cas provide technical support for it.

Retour à la liste