I am writing a script for calculating a precipitation index using satellite imagery, and am wondering if it can be applied to an arbitrary area or if it should be constrained to a basin. My gut says that it should depend on your research question and the information you derive from the results, but it would be good to hear an expert's thoughts! To answer Earth science questions you'd probably want to isolate the basin, but for applications outside Earth science (e.g. questions about crop yields in an administrative area) I think it could be useful.
P.S. I will post the application here when I'm done with it, the idea is to make this type of analysis accessible to people without this expertise.