Methods of validating a questionnaire
Development of a valid and reliable questionnaire is a must to reduce measurement error.
Groves (1987) defines measurement error as the "discrepancy between respondents' attributes and their survey responses" (p. Development of a valid and reliable questionnaire involves several steps taking considerable time.
Which type of validity (content, construct, criterion, and face) to use depends on the objectives of the study.
The following questions are addressed in Step 4: Addressing these questions coupled with carrying out a readability test enhances questionnaire validity.
Scales are devices used to quantify a subject's response on a particular variable.
As a result of Steps 1-3, a draft questionnaire is ready for establishing validity.Reliability is established using a pilot test by collecting data from 20-30 subjects not included in the sample. Data collected from pilot test is analyzed using SPSS (Statistical Package for Social Sciences) or another software. These are "correlation matrix" and "view alpha if item deleted" column. Systematic development of questionnaires is a must to reduce many measurement errors.Following these five steps in questionnaire development and testing will enhance data quality and utilization of research.