I am running a case-control interventional study where the dependent variable/ outcome is a proportion. The cases were given an intervention whereas the controls were not and measurements were taken at the beginning (pre-) and end (post-) of intervention (or in controls, at the same time as cases).

Am getting slightly confused regarding the best test to use to determine whether there is a significant difference in the differences in proportions pre- and post-intervention for the case vs. control groups.

My initial thoughts were that the pre-post differences in proportions in themselves can be thought of as continuous variables, and therefore comparing the means of the differences using a standard independent samples t-test would be appropriate. However, on reflection I am now not so sure because they are proportions!

Would appreciate some help asap!


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