1、 Data preparation

In order to demonstrate how to use IBM SPSS Statistics to conduct a difference test between high and low groups, we will explore whether there is a significant difference in English scores between high and low groups. The data includes two variables: student ID and student English score. Some of the data are shown in the following figure.

Figure 1 Data Display

2、 Analysis steps

Before conducting analysis, it is necessary to rank students' grades in order of high or low. Click on "Data" - "Case Sorting" in the top menu bar of SPSS, load the English score variable into the sorting criteria text box, and select descending sorting order.

Figure 2 Case sorting

Select the top 30% and bottom 30% of the English score as the critical points, and sort them in descending order above to obtain a critical point score of 76 for the bottom 30%. Similarly, use ascending order to obtain a critical point score of 88 for the top 30%.

Divide students into high and low score groups based on the above critical points. Click on the top menu bar of SPSS, select "Convert" ->"Re encode Different Variables", load the English score into a numerical variable ->output variable text box, and enter the variable name text box for high and low grouping. Then click on "Change Quantity".

Figure 3 renumbered

Click on the old value and the new value, and set the first 30% of the new value flag as 1 and the last 30% as 2. Set three new values for each level: 1 and 2. For example, enter 2 in the "Value" text box for the new value, and set the range of 88 and 96 in the text box for the old value range.

Figure 4: Setting New Values

Click on the top menu bar of SPSS, select "Analyze" - "Compare Means" - "Independent Sample T-Test", to open the Independent Sample T-Test. Load the 'English score' variable into the test variable text box, load the 'high and low scores' group into the grouping variable, and click' Define Group 'to complete the settings.

Figure 5 Independent sample t-test

3、 Result analysis

Click the confirm button to obtain the analysis results. Firstly, we can see the group statistics, including mean, standard deviation, and mean standard error, all of which are within an acceptable range

Figure 6: Group Statistics

The F-test in the following figure is a homogeneity of variance test, with a significance value of 0.835. At the 0.05 level, the null hypothesis cannot be rejected, indicating that the variance is homogeneous. It can be seen that the significance values in the first row are all less than 0.001, indicating a significance level of less than 0.05, rejecting the null hypothesis and suggesting a significant difference in English scores between the high and low groups.

Table 7 Independent Sample Test