Performing the Runs Test Using SPSS

OBJECTIVE In this lecture, you will learn the following items: How to perform a runs test using SPSS

We will analyze the data from the example earlier using SPSS Define Your Variables First, click the “Variable View” tab at the bottom of your screen. Then, type the names of your variables in the “Name” column. As seen in Figure 4, we call our variable “gender.”

Next, we establish a grouping variable to differentiate between males and females. When establishing a grouping variable, it is often easiest to assign each group a whole number value. As shown in Figure 5, our groups are “male” and “female.” First, we select the “Values” column and click the gray square. Then, we set a value of 0 to represent “male” and a value of 2 to represent “female.” We use the “Add” button to move each of the value labels to the list. We did not choose the value of 1 since we will use it in step 3 as a reference (custom value) to com pare the events. Once we finish, we click the “OK” button to return to the SPSS Variable View.

2 Type in Your Values Click the “Data View” tab at the bottom of your screen (see Figure 6). Type the values into the column in the same order they occurred. Remember that we type 0 for “male” and 2 for “female.”

3 Analyze Your Data As shown in Figure 9.7, use the pull-down menus to choose “Analyze,” “Nonparametric Tests,” “Legacy Dialogs,” and “Runs. . . .”

The runs test required a reference point to compare the events The runs test required a reference point to compare the events. As shown in Figure 8 under “Cut Point,” uncheck “Median” and check the box next to “Custom:.” Type a value in the box that is between the events’ assigned values. For our example, we used 0 and 2 for the events’ values, so type a custom value of 1. Next, select the variable and use the arrow button to place it with your data values in the box labeled “Test Variable List.” In our example, we choose the variable “gender.” Finally, click “OK” to perform the analysis.

4 Interpret the Results from the SPSS Output Window The runs test output table (see SPSS Output 9.1) returns the total number of observations (N = 20) and the number of runs (R = 13). SPSS also calculates the z-score (z* = 0.689) and the two-tailed significance (p = 0.491).

5 Determine the Observation Frequencies for Each Event In order to determine the number of observations for each event, an additional set of steps is required. As shown in Figure 9, use the pull-down menus to choose “Analyze,” “Descriptive Statistics,” and “Frequencies. . . .”

Next, use the arrow button to place the variable with your data values in the box labeled “Variable(s):” as shown in Figure 10. Like before, we choose the variable “gender.” Finally, click “OK” to perform the analysis.

The second output table (see SPSS Output 2) displays the frequencies for each event. Based on the results from SPSS, the runs test indicated that the sequence was random (R = 13, n1 = 10, n2 = 10, p > 0.05). Therefore, the science teacher randomly chose between males and females when calling on students.

SUMMARY In this chapter, we explained how to perform the procedure using SPSS.