SOCR EduMaterials AnalysisActivities Wilcoxon

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Two Independent Sample Wilcoxon Test Example

We will demonstrate Two Independent Wilcoxon Test with a SOCR built-in example. This example is based on the data taken from "Mathematical Statistics and Data Analysis" by John A. Rice, Second Edition, Ducbury Press, 1995. (Page 390)

Note that this text book uses the data for a Two Independent T-Test but we're only taking the data to demonstrate the Wilcoxon Two Independent Sample Rank Test.


Here's the steps of the activity:

1. Click on Two Independent Sample Wilcoxon Test at the left panel's combo box.

SOCR AnalysisActivities TwoIndepW Chu 051707 Fig1.gif


SOCR AnalysisActivities TwoIndepW Chu 051707 Fig1A.gif


On the right panel, first click on EXAMPLE 1 and next click on "Data" to retreive the demonstrated example. This is the example we'll be looking at.Note that the data are difference of B - A.

SOCR AnalysisActivities TwoIndepW Chu 051707 Fig2.gif


2. Click on the "Mapping" button to get to the "Mapping" panel. Click on "ADD" under VARIABLE 1 and to VARIABLE 2 add the variables for Two Independent Sample Wilcoxon Test. We care about the difference, so which on goes to VARIABLE 1 is arbitrary. You can just add column A to VARIABLE 1 and B to VARIABLE 2. Here, the computer will set difference = Variable 2 - Variable 1. If you like the substraction to go the other way around, simple assign VARIABLE 1 and VARIABLE 2 in a different way.


SOCR AnalysisActivities TwoIndepW Chu 051707 Fig3.gif


3. Click on "Calculate" then "Result" to see the results.


SOCR AnalysisActivities TwoIndepW Chu 051707 Fig4.gif


Questions for students: By looking at the test results, what do you think about the data? What can you say about the two different shoe materials?