One-sample Wilcoxon Test

The Wilcoxon signed-rank test is used to test whether the median for a variable has a particular value. Unlike the one-sample t-test, it does not assume that the observations come from a Gaussian (normal) distribution.

To perform a one-sample Wilcoxon test

Choose Statistics __image\ebd_ebd11.gif Compare Samples __image\ebd_ebd12.gif One Sample __image\ebd_ebd13.gif Wilcoxon Signed Rank Test. The dialog shown below appears.

__image\wilcox.gif

The One-Sample Wilcoxon Test dialog has the following options:

Data

Data Set

Select a data set from the dropdown list or type the name of a data set. You can also type into the Data Set edit field any expression that evaluates to a data set.

Variable

Select the column to which the test will be applied.

Hypotheses

Mean Under Null Hypothesis

Enter the assumed population mean of Variable.

Alternative Hypothesis

Select the alternative hypothesis. For example, to perform a one-sided test against the alternative hypothesis that the mean of Variable is greater than the null hypothesis mean, select greater.

Options

Use Exact Distribution

Select this to use the exact distribution of the test statistic to compute the p-value. Note that this option cannot be used when there are ties in the data.

Continuity Correction

Select this to use a continuity correction in the normal approximation to the distribution of the test statistics.

Results

Save As

Enter the name for the object in which to save the results of the analysis.

Print Results

Select this to print out the results of the analysis in the designated output window.

Related S-PLUS language functions

wilcox.test, t.test