t Tests with SPSS

This exercise asks students to look at the attitude data set used in Chapter 8 and to analyze some data employing the t test for independent samples.  You may complete the assignment by using either SPSS or Excel.  If you wish to use Excel do not use this page, but go to the page t Tests with Excel.

The background of the study is as follows.  A researcher was interested in whether non sequitur fallacies were persuasive. Argumentation theorists will tell you that such fallacies should not influence people, but they have serious doubts about responses of people who have never studied fallacies. Thus the directional hypothesis in this study is that arguments using non sequitur appeals will produce lower levels of attitude change than arguments non using non sequitur appeals. In this study a couple of arguments were composed and in the experimental treatment, respondents listened to a speech that include non sequitur reasoning focused on largely irrelevant information.  In the control condition, the non sequitur reasoning was deleted, leaving a fairly sound argument.   These two conditions are the levels of the independent variable. The variable that identifies this fact is "falexper" (1= with the fallacy presented to subjects; 2=without the fallacy presented to subjects). The dependent variable is "attitude" toward the topic (as created in chapter 8), which is the sum of the scores of the scales "wise-foolish;" "good-bad;" "positive-negative;" and "beneficial-harmful".

The task in this activity is to determine if there is a significant difference between the two conditions in this experiment. Complete a t test with alpha risk at .05, one-tailed.


bulletIf you have not already done so, go to the Data Sets location and download the file "ATTITUD1.SAV" under the "SPSS Files" category on the "Data Sets" webpage.
bulletStart your SPSS program.  From the "File" menu load the data file "ATTITUD1.SAV" from the location where the you saved it.
bulletTo compute this t test, click on the "Analyze" menu, and on subsequent menus that appear, click on "Compare Means" and "Independent-Samples T Test." In the dialog box titled "Independent-Samples T Test" place "attitude" in the "Test Variable(s)" list.

In the same dialog box, place "falexper" in the "Grouping Variable" list.  

bulletClick the "Define Groups" button.  On the "Define Groups" dialog box, click on the "Use specified values" button.  Enter 1 in the "Group 1" field and 2 in the "Group 2" field.








        Click on "Continue" and then "OK" on subsequent boxes.

bulletSave your output and answer the following questions:

What is the observed t value?____________

Is there a significant difference between the groups?____________