Dear Mark,
Thank you so much for responding so quickly and sorry for a naive question - but where do I find this 'Validation role' in the LDA platform? I'm quite new to JMP, and not everything is clear to me.
The only thing I found is the option on the main tab where I select variables for LDA. There I can tick the box 'Validate by excluded rows' which selects Train/Test data based on the validation column I've created. But this offers only a one-off split based on this column, not any iterative validation options (like leave-one-out or k-folds or Monte Carlo I'd like to run). But again, maybe I'm missing something very obvious here?
I didn't want to duplicate the posts, sorry about that! I wasn't sure if anyone will answer to my response to a very old post!