content validity and its estimation

background: measuring content validity of instruments are important. this type of validity can help to ensure construct validity and give confidence to the readers and researchers about instruments. content validity refers to the degree that the instrument covers the content that it is supposed to measure. for content validity two judgments are necessary: the measurable extent of each item for defining the traits and the set of items that represents all aspects of the traits. purpose: to develop a content valid scale for assessing experience with computer usage. methods: first a review of 2 volumes of international journal of nursing studies, was conducted with only i article out of 13 which documented content validity did so by a 4-point content validity index (cvi) and the judgment of 3 experts. then a scale with 38 items was developed. the experts were asked to rate each item based on relevance, clarity, simplicity and ambiguity on the four-point scale. content validity index (cvi) for each item was determined. result: of 38 items, those with cvi over 0.75 remained and the rest were discarded resulting to 25-item scale. conclusion: although documenting content validity of an instrument may seem expensive in terms of time and human resources, its importance warrants greater attention when a valid assessment instrument is to be developed.