Having developed a questionnaire, whether this is to assess food/nutrient intakes or for any other purpose, it is essential to carry out a feasibility study (pilot study). This should be done using similar subjects to those who will take part in the main study. The aims of the pilot study are to ensure that subjects will be able to answer the questions in a reasonable time and to identify any questions likely to pose difficulties for the main survey. The pilot study may be useful in identifying food items that are rarely consumed in the population and which could therefore be omitted from the questionnaire, reducing its length. It may also be helpful in identifying any additional foods consumed in the population which should be included in the questionnaire.