ABSTRACT
Designing a good questionnaire is very difficult and time-consuming. It is often better to search for an existing questionnaire/data collection instrument/health measurement scale that has already been tried, tested and validated. Various texts and the internet can be used to identify many such ‘ready-made’ instruments. Postal questionnaires allow subjects plenty of time to complete the forms, in the comfort of their own home. However, it should be remembered that postal questionnaires may achieve a response rate of 25% or less. They are also expensive, because one need to cover the cost of postage to the patient, plus the cost of a stamped addressed envelope. If patients are asked to complete and hand in the form before they leave the premises, a much better response rate can be achieved. When using interviewers, one must ensure that they all receive training in how to administer the questionnaire.
