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.
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.
Unstructured format may be used at clinical setting however structured questionnaire is preferred for epidemiological studies as same data from all respondents need to be analyzed and measured.
It is essential to word the questions in a way that they can easily be understood by participant and should be according to their educational level and culture.
A valid questionnaires must have following characteristics (i) simplicity and viability (ii) reliability and precision in the words (iii) adequate for the problem intended to measure (iv) reflect underlying theory or concept to be measured and (v) capable of measuring change.
Type of Questions: A questionnaire is a written document to gather information irrespective of mode of administration.
Translation is not a mechanical work and should not be done on word to word bases across languages.
It is important to understand the local context, specific issues and cultural meanings which language carries.