Validating an instrument
Back translation helps in evaluating the quality of the translation.
Open-ended questions allow respondents to answer them in any way they want.Introduction and Objectives: Measurement is an essential activity of medical science.In order to acquire data about people, objects, and events proper data collection tools need to be designed which can measure things of scientific interest.It is an efficient way to collect data, the investigator should be certain on what is required and how to measure the variables of interest.As a first step it is always recommended to do a literature search on previously used validated questionnaires that can be administered in similar settings and capture variables that are of interest according to the study hypothesis.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.
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.
Essentially there are three types of validity i) content validity, ii) criterion- related validity, and iii) construct validity.
Translation should not only be concerned with translating meanings, but it should also understand how the language is tied to local realities and literary forms.
The term back translation is highly recommended in questionnaires related to health surveys.
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.