Page 44 - A Step-By-Step Guide to Questionnaire Validation Research

2.1 Content validity

Content validity is an assessment of the degree to

which each item or question is able to measure what it is

supposed to measure. Therefore, the content validity of a

questionnaire should be assessed by a subject matter

expert within a particular field and so it will be evaluated

by using a qualitative approach (Lawshe, 1975). For

example, if the questionnaire is related to quality of life for

diabetic patients, then an endocrinologist or family

medicine specialist will be a suitable subject matter expert

to determine its content validity. It is commonly accepted

that by the time the questionnaire has been accepted for

publication, the content of all the items in the

questionnaire shall have already been determined to be

reasonably accurate in measuring what they are supposed

to measure.