Hello! I have a question similar to the one posted here that was never followed up on: [afni.nimh.nih.gov]

I am struggling to understand what to choose for a sub_TR value for a beginner gPPI analysis I am working on. The experiment I am working on does not have stimulus onset times synced with TR grids, so I believe this is an option I need to use. The example on the help page (https://afni.nimh.nih.gov/CD-CorrAna) includes an example of using sub_TR of 0.1 initially, but then in the bottom example uses a value of 1 and states that it is "upsampling the data because of stim duration of 3s". I am having a hard time understanding what this means and why the value of sub_TR=1 was chosen (over something like 0.1) given the context provided. Let me know if someone is able to provide clarification, and/or input to help understand this conceptually.

Thank you,
Ian