I've read posts referring to high drop out rates on doctoral courses. I wonder if anybody had an clue of what percentage this was? Obviously people might drop out for a whole variety of reasons (personal, financial, research problems etc) but I would be interested to know from your experiences of other people or yourselves dropping out what are the key contributors....I haven't even started out yet and I'm already having the 'what if my rsearch hits a brick wall' nightmare!