Introduction
Measurement is an essential activity in medical science. To acquire data
on people and events, and to measure the intended scientific interest,
the appropriate data collection tools need to be designed. Questionnaire
is one of the most crucial 1.
Due to the subjective nature of the results that are being measured, for
example, quality of life (QoL) impact or disease severity, it is
increasingly necessary to have valid, reproducible and reliable methods2. There are several instruments (indexes,
questionnaires, scales) which can measure a certain characteristic in
health. In the last decade, the impact and use of these instruments has
increased 3 and their importance is increasingly
emphasized. It is important to know the opinion of patients and what
they feel daily, and also their opinion on the care provided by health
professionals and the service they use, in order to create treatment
goals or improve the care provided.
The composition of a questionnaire is always much more complex than
expected and great attention is needed to its flow, shape and length.
Accordingly, it should be assessed whether the questionnaire will
measure quantitative or qualitative data, and which method of
administration 1.
There is no guidelines simply focus on the validation of questionnaires.
There are some reviews or task forces. Nevertheless, looking at some
validation studies, there are different methods or techniques to develop
it, which may cause some confusion. The aim of this review is to
synthetize some of these information, to be used as a simple guide for
researchers and/or clinicians facing the need to validate a
questionnaire.