I am trying to see if the change in GFR (continuous variable) from baseline to 3 years later (total of two time points) is different between my control and intervention groups. The difference between the two groups are significant at both time points individually using independent two sample t-test.
Thank you all for your help!
Calculate change values (post-pre) for both groups and run independent samples t-test between PAIR 1 and PAIR 2. If you want to check differences in the two individual groups (pre and post) run paired samples t test for PAIR 1 and then again for PAIR 2.
Calculate change values (post-pre) for both groups and run independent samples t-test between PAIR 1 and PAIR 2. If you want to check differences in the two individual groups (pre and post) run paired samples t test for PAIR 1 and then again for PAIR 2.
The use of the t-test is not ideal since time series data are always correlated and not independent. The more ideal thing is to fit an arima model to the pre-intervention data. Obtain post-intervention forecasts on its basis. Model the difference between the post-intervention observations and forecasts for the transfer function. Statistical significance of the function is an indication of that of the intervention impact.
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