# Using t-test for comparing Likert responses before and after intervention

I am testing a hypothesis that states that participants after an intervention will be more likely to perceive themselves as being at risk for disease. Two questionnaires will be used. One will consist of 5 questions and will measure perceived susceptibility and the the other will consist of 7 questions and will measure perceived disease severity.

I think the best way though uncertain to analyze these two questionnaires which are rated on 5-point Likert scales is to use a $t$-test but I am not sure of how or the best way to do it. I am looking for suggestions.

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Now that I re-read the question and its title, it's not clear to me where the pre-post measurement process arises? Do you intend to use the two questionnaires twice (before and after intervention)? –  chl Dec 26 '11 at 19:37
The answer is yes. I will be using the same instruments pre and post the intervention. –  tiffiny Dec 27 '11 at 1:22
Are these questionnaires considered validated in your study population? Are there standard ways to score each (e.g., arithmetic sum of responses, weighted sum, different subscales)? –  Ming-Chih Kao Dec 27 '11 at 5:48
I will have to do a pilot study initially. The scores will be tabulated and separated by the overall number of participants who answer each question to determine the score rates for perceived severity and susceptibility and additonal demographic questions. –  tiffiny Dec 27 '11 at 15:35