I am trying to compare pain estimation within two groups. I am following a random control trial research and have to groups for that i.e. experimental and control one. Each group has the same variable i.e. pain estimation measured before and after. I want to check the significance of the same variable measured before and after within each group but NOT between groups as independent sample t test does (is meant for). How do I achieve this on SPSS?
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$\begingroup$ Before getting an answer I had a little idea to define pain variables for each group e.g var_pain_experimental_before, var_pain_experimental_after as 1st pair and the same for control: var_pain_control_before, var_pain_control_after as a 2nd pair $\endgroup$– Web MasterCommented Apr 5, 2020 at 20:06
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$\begingroup$ Your comment seems to contradict your question. // Can you do 'half' of this project by using only the Control group: comparing Control Before to Control After? If there are 20 Control subjects, you'd be looking at 20 differences $\mathrm{Diff} = \mathrm{After}- \mathrm{Before}.$ // if that is the case then you have two choices: (a) A paired t test of $\mu_A = \mu_B$ vs $\ne.$ (b) A one-sample t test on the 20 Dif scores with null hypothesis $\mu_D = 0$ vs $\ne.$ // Before doing any t test make sure there are no far outliers in your data. $\endgroup$– BruceETCommented Apr 5, 2020 at 21:19
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$\begingroup$ @BruceET it seems like you trying to put my on a good track and may seem contradictive in between question and comment but as I said I need a paired t test for same variable in each group but not between groups, unless there is a choice to use some variance test on SPSS that would compare the signifinace (if any) of the following one variable variances measured before and after. In conclusion I don't think I could use only Control subjects, I have only 20 subjects equally distributed in two groups, so each is n=10. Too few. $\endgroup$– Web MasterCommented Apr 6, 2020 at 8:54
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Use a paired-samples t-test in SPSS to compare the 'before' and 'after' scores within each group (i.e. one t-test to compare 'control_group_before' and 'control_group_after', and another for the two scores in the experimental group).
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$\begingroup$ Just done this nearly a week ago. But thanks anyways. $\endgroup$ Commented Apr 15, 2020 at 20:57