Remember that descriptive responses will take considerably longer to analyse than replies to simple questions, which is why we never conduct as many interviews as we do questionnaires. We go for depth or breadth. Questionnaires provide breadth with some detailed description; for real depth we need interviews or observations. Think about the holistic picture not a list of individual questions. Design your questionnaire with an overall function so you can use techniques such as funnelling, which 'starts off with a very broad question and then progressively narrows down the scope of the questions until it comes to some specific points'