SPSS Tutorial 01 Independent Samples t -test The comparison of two independent samples can be conducted in SPSS to draw conclusions about the difference between the two populations. To see this, let’s work through the example below from the Visual Learner media piece for two independent samples (the data can be found in the Visual Learner media piece). An advertising company wishes to place billboards for their new client in cities where they will do the most good. They believe this means cities with the youngest population for the new product. They wish to compare Phoenix and Los Angeles. They took a random sample of adult residents from each city. The ages of 45 LA residents and 40 Phoenix residents are shown below. The researcher wishes to prove that the mean age of the adult residence of Phoenix is less than the mean age of the adult residence of LA. You will notice that the data is entered differently for this type of problem. Two columns of data are used, one for Phoenix and one of Los Angeles with the ages listed in those columns. SPSS requires one column for the variable of city and one for the variable of age. Numerical values are needed for the city, so let 1 be Phoenix and 2 be LA. Once the data has been entered, you are ready to begin the analysis. Click on Analyze – Compare Means – Independent Sample T Test … The Independent-Sample T Test box will open. In this example, age is the variable you are interested in testing so it is moved to the Test Variable(s) box. City is then moved to the Grouping Variable box.