Validity is the degree to which an instrument measures what it is supposed to measure. Content validity (CV) determines the degree to which the items on the measurement instrument represent the entire content domain. Experts familiar with the content domain of the instrument evaluate and determine if the items are valid. A CV ratio (CVR) is a numeric value indicating the instrument’s degree of validity determined from expert’s ratings of CV. One rule of thumb suggests that a CVR of at least 0.78 is necessary to deem an item or scale as valid.

In order for a research study to provide accurate and meaningful results, the instrument used to test the hypothesis must be valid. Use of a measurement instrument that is not valid may produce ...