Wilcoxon (Matched Pairs)

The Wilcoxon SIGNED-RANKS TEST is used with MATCHED PAIRS of data. It is used to test for differences in the population distributions.

The following notation applies when using this test:

T = the SMALLER of the sum of the absolute values of the negative ranks or the sum of the positive ranks

d = for each pair of data, the difference found by subtracting the second value from the first

n = the number of pairs of data for which the difference d is not 0

IMPORTANT: This test requires that paired data are already listed in the STATDISK data window

If the data are not already there, close this window and enter or open data sets so that they are listed in columns of the STATDISK Data Window. (To open a data set from Appendix B in the textbook, click on "Datasets" at the top. To manually enter a data set, click on Data, then click on Sample Editor. The data can also be copied into STATDISK from another application, such as Minitab or Excel.)

Significance (level): Enter a positive value in decimal form, such as 0.05.

Identify the two columns containing the sample data. The default values are 1 and 2, but they can be changed by clicking on the small box to the right of the default value.

Click on the Evaluate button to obtain the results.

Click on the Print button to print the results.

Click on the Plot button to obtain a graph showing the test statistic and critical value. NOTE: A graph will be generated only when the normal distribution approximation is used.

To close the window, click on the X at the top of the module window.