Introduction and Objectives: Measurement is an essential activity of medical science.
A questionnaire undergoes a validation procedure to make sure that it accurately measures what it aims to do, regardless of the responder.
Valid questionnaire helps to collect better quality data with high comparability which reduces the effort and increase the credibility of data.
Translation back to the source language is done by another translator who is unaware of the source language version.
Validity: Validity is the degree to which an assessment measures what it is supposed to measure.
It is extremely important for a researcher to know the importance of a proper questionnaire and whether it measures what it is intended to measure.
Composing of a questionnaire is always much more complex than expected and great attention is required to its flow, format and length.A questionnaire could be structured, in which all the participants are asked same questions in the same way, this is usually interview based questionnaire format.The other type is unstructured questionnaire and questions may vary at the discretion of the interviewer.Translation of a questionnaire is essential if an instrument is not available in a language understood by the target population.The initial stage of translation is a source language questionnaire, from which translation in required language is done.Validity is a complex topic and it is beyond the scope of this paper to explain it in detail, however to make the readers acquainted we have described it briefly.