What is the best T test to use for my data?

Hi, I'm trying to work out the correct non parametric T test to use for my data. My data is made of two large groups. Each value in the first group has a corresponding later value e.g. it is showing the chance in frequency from point 1 to point 2 over time, there is many different points for each of the 2 groups though.
What I want to show is that points in group 2 are overall significantly lower in frequency than their corresponding point in group 1. Calculating mean here felt kinda pointless but idk. I'm going to be using Rstudio or prism for the analysis.


Less is more. Stay pure. Stay poor.
So you have one group of people with repeated measures and you want to compare their change in Y between two periods?

Is the time between the periods the same for everyone and did you have any loss-to-follow-up?
in theory yes that is the scenario. the time between the periods is the same. It is testing the same thing at two time points (group one then group 2). I'm not sure what you mean by loss to follow up?