As discussed in a previous issue a survey involves directly collecting information from people (or sometimes organisa- tions) whom we are interested in.1 The types of information will take account of the people’s or organisations’ level of knowledge, attitude, personalities, beliefs, or preferences. Questionnaires are wide- ly used to collect such information. Well designed questionnaires are highly struc- tured to allow the same types of informa- tion to be collected from a large number of people in the same way and for data to be analysed quantitatively and systemati- cally. Questionnaires are best used for collecting factual data and appropriate questionnaire design is essential to ensure that we obtain valid responses to our questions.