** Wilcoxon Signed Ranks Test**

If you feel a bit insecure about calculating and interpreting the inferential statistics required for this assessment, do not panic. Vassarstats is a really easy program to use, and it does not require you to go back and review the calculus.

First, go to the **Vassarstats site**.

To calculate the Wilcoxon Signed Ranks Test, click on **"Ordinal Data"** in the left-hand margin.

The Wilcoxon Signed Ranks Test is used for **repeated measures designs**. Click on the test. The program will ask for the size (n) of the sample. In order to practice using the test, enter a size of 9.

Enter the following data in the boxes for Xa: 15, 12, 13, 15, 17, 18, 14, 19, 20. Then enter the following data for Xb: 25, 27, 29, 30, 30, 22, 28, 29, 30.

After you have entered the data, click on the "calculate" button.

Now for the final step. The IA’s require that students predict the direction of the hypothesis – that is, their hypothesis argues that x increases the effect on y or decreases the effect on y. Therefore, you are going to use the values under "directional test."

To interpret the results, you need to compare the W score – in this case -45 to the values in the table below. You will see that for a directional test at a significance level of p<0.05 for a sample of 9 a W of 29 or higher is required. You should always use the absolute value of the W score – that is, ignore the fact that in this case it is negative. Since our value is greater than 29, we can say that our data is significant at p< 0.05. If we then move across the chart, we see that our data is greater than 35, 39, and 43. Therefore, we can conclude that our data is significant at p< 0.005. That is, there is less than a .05 percent chance that our results are due only to chance

not have exceeded the value for p<0.05. Then we would have concluded that our data is not significant, and that our null hypothesis is retained.