What is define validity?

Validity refers to the extent to which a measure or an assessment accurately and effectively measures what it is supposed to measure. It is one of the most important criteria to determine the usefulness of an assessment or measurement method. The validity of a test or instrument is determined by comparing the measurement results with an external criterion, which is considered the gold standard for the construct being measured. There are different types of validity, including face validity, content validity, criterion validity, and construct validity. Face validity refers to the extent to which a measure appears to measure what it is supposed to measure, while content validity refers to the degree to which a test or assessment measures the content it is supposed to measure. Criterion validity refers to how well a measure or instrument predicts an external outcome or criterion. Construct validity is the degree to which a test or instrument measures the intended construct or underlying theoretical concept. Overall, validity is a critical aspect of measurement and assessment, as it ensures that inferences and conclusions made based on measurement results are accurate and dependable.