4/20/2023 0 Comments Intsalling pspp statistics![]() It would be best to report this result as p <. Having a zero p value is not really possible, but PSPP can't make a judgment about something impossible. The students who get the new math teaching approach are doing better than the students who received the older teaching approach. This is a statistically significant difference. We will reject the null hypothesis because this p value is less than. 259, so we will use the equal variances assumed version (marked in blue). The Levene's test p value for this example is p =. When this test is nonsignificant use the equal variances assumed version. How can you tell which version to use? The Levene's test part of the output will give you the answer. For most situations we will use the equal variances assumed version. This gets a little tricky because there are two versions of the test: Equal variances assumed and equal variances not assumed (see the rows). The upper table shows some useful group statistics, like means and standard deviations. Press the Continue and OK buttons to perform the analysis. ![]() This is represented by the "cut point" option. Note that PSPP has a feature for taking a continuously scaled variable and form two groups from a cutoff point if desired. Enter the coding scheme values, which are 0 and 1 for our example. The second step is to inform PSPP how the groups are represented. This field represents the independent variable and group membership. Move the "math groups" variable to the Grouping Variable field. This field is for the dependent variable. Move the "math experiment" variable right to the Test Variable(s) field. The first step is to choose the variables. Choose the independent-samples t-test command by going to Analyze > Compare means > Independent Samples T Test. We will test for differences between the experimental group and the control group by using the independent-samples t-test. The 1 value is for people in the experimental group. The 0 represents people in the control group. The variable IndSampleGroups has a 0 or 1 coding scheme for representing the group membership. The variable IndSample is the dependent variable with the math test scores. Here is what the data might look like in our example. A second categorical variable will be needed to code for which group each student is in, experimental or control. In PSPP, we will need a variable that represents the math scores (dependent variable). The results will be compared to see if the new method is effective. Both groups will be measured on a standardized math test at the end of the semester. The experimental group will get the new instructional method. The control group will get the older, standard method of instruction. We will form two equivalent groups of students by randomly assigning them to different classes. Let's say that there is a new method of math instruction that is believed to be superior to older methods of instruction. We could not, however, make strong conclusions about whether a particular kind of instruction was effective or not.įor this next example we will do a true experiment. It is an interesting comparison for local educators. The preceding example, which compared a local sample to a population mean, is not a true experiment. PSPP for Beginners PSPP for Beginners Independent-samples t-test
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