# Thread: Which statistical tests are appropriate: Group means before and after treatment

1. ## Which statistical tests are appropriate: Group means before and after treatment

I am trying to find out what statistical tests to run on a set of aggregate data (no individual data) on 3 different groups, variables are summarized below: Group 1 in site 1: Mean value (blood sugar) of the total sample before treatment, and mean value (blood sugar) of the same group after treatment Group 2 in site 2: same as above Group 3 in site 3: same as above

I want to know if it makes sense to run the following analysis on the above data:

1) Paired t-test on each group separately for the group difference in blood sugar means after treatment and before treatment (to test if any increase or decrease in the whole group average is statistically significant) 2) where I start struggling is when I think of the tests to apply for the difference between the groups. I can calculate absolute difference in the means after and before treatment for each group, have then difference of the means after and before in group1, difference of the means after and before in group 2 and same for group 3. Can I run an ANOVA on the difference means between the three groups (mean diff of means after and before group 1 vs mean difference of the means after and before for group 2 vs the one of group 3)?? If yes what other data do I need?

2. ## Re: Which statistical tests are appropriate: Group means before and after treatment

Hi Pamela. You will need much more than the group means to do any statistical testing. Even knowing the group standard deviations and the number of patients will not be enough because you have multiple data from the same patients. If you had the between group correlations you would be on the way to doing tests, but ideally you need the original data, or if it is confidential, perhaps a coded version of it. kat

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