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151  The independent t-test - this is used to compare means from independent sample groups of individuals. This test compares the means between two unrelated groups on the same continuous, dependent variable. For example, one could use an independent t -test to understand whether customer service differs based on gender. Alternately, one could use an independent t -test to understand whether there is a difference in testing depression based on educational level.  The paired t-test - is used in comparing the means of the observations from the same individuals. Performing a T -test in SPSS 1. Go to Analyze Compare Means 2. This brings the different t -tests that is one-sample test , Independent-Samples T-Test and paired t- test ... 3. Clicking on the desired t-test will bring a dialogue box for the selected t -test. An example for independent t -test is as follows: a) In the dialogue box − typical in all SPSS procedures that the box on the left side lists the variables in the data file. b) Click the name of the dependent variable for the analysis and click on the arrow button to move the variable to the marked Test Variable(s). c) After that, click the name of the independent variable and put it in the grouping variable. In this dialogue box, the groups need to be defined. Here, the box will pop-up to specify what is group one and two. d) Click on Continue that will take to the independent test main dialogue box and then click OK to get the output. e) The output will generate several statistics, including the size of the effect (effect size) in terms of the differences recorded between the variables. The effect size is simply a way of quantifying the size of the difference between two groups. It is particularly valuable for quantifying the effectiveness of a particular intervention, relative to some comparison. It allows to move beyond the simplistic such as ‘Does it work or not’ to the far more sophisticated, ‘How well does it work in a range of contexts’ (Coe, 2002). The output from SPSS of the t - test analysis does not provide the size of the effect and SPSS has no functionality to be selected in order to produce the effect size. However, from the output, effect size can be calculated using the information that