How long does it take you to describe your research question or aim? If it takes more than one sentence, you don't understand what you are doing well enough. Too often candidates rush in with an ill-specified question or aim. This leads to lots of ill-focused activity, much of which will be wasted, and is a major contributory factor to students giving up along the way. Your question or aim may evolve, but any time during your study, I would expect you to tell me what your research question or aim is in one succinct statement or question.