How to determine if I'm just incompetent, or if my work is more difficult than expected? I'm a PhD student in my (planned) last year, with no journal publications until now (one rejection, though, due to not having the level of research the journal aims for). Several things which were planned to be finished already in the first year are still not finished, partly because they were more difficult than expected, partly because we did not have the material at the time we should start them (and now we do not have time for starting them, because we still have unfinished tasks). My supervisor keeps telling me that I should have finished those tasks already a long time ago, including several suggestions and changes which were made during the development.
Thus, I slowly started to doubt myself, and am not sure anymore if those tasks are more complex than expected, or if I'm just incompetent and unable to complete them at all. It doesn't help either that my supervisor has no knowledge about the field the tasks are located in (he's an experimentalist, the current tasks are involving both heavy computational tasks and experimental tasks with materials no one in the university has worked with before).
Therefore, I was wondering if there is a way to determine if those tasks are just more complicated than expected, or if I'm just too slow for completion due to incompetence or lack of working hours?
let me introduce you to my friend the impostor syndrome. In all likely-hood you are behind but not incompetent. From my experience, almost all people I interact with in academia have something that is past it's "due date". I think you need to take a deep breath and remeber that what you're doing is dificult and you should expect some (if not a lot) of trouble.