VALIDITY

Validity is an important characteristic of a scientific instrument. The term validity denotes the scientific utility of a measuring instrument, how well it measures, what it purpots to measure. Validity has surplus meaning; some take it to mean all things that are good about a measuring instrument rather than to specify how well the instrument has met the standards by which it is judged.

According to Anastasi :- Validity refers to the degree to which a test measure, what it purpots to measure. Validation always requires empirical investigation, with the nature of measure and form of validity dictating the needed form of evidence. Validity usually is a matter of degree rather than all or none property and validation is an unending process

There are three purposes of a test; corresponding to three purposes there are three types of validity PURPOSES To measure the level of attainment on some learning achievement or course curriculum program. To assess/predict behaviour in real life setting. To measure some psychological construct or trait. VALIDITY TYPES Content validity Criterion validity Construct validity

Types of validity 1.CRITERION VALIDITY:- Criterion validity indicate the effectiveness of a test in predicting an individual’s performance in specified activities. The criterion measure against which test scores are validated may be obtained at approximately the same time as the test scores or after a stated interval. To know or get the criterion validity of a test; test scores correlated with criterion scores.

There are two types of criterion validity:-  Concurrent validity:- This type of validity is relevant to diagnosis of current status.  Predictive validity:- This type of validity is for prediction of future outcomes.

2. CONSTRUCT VALIDITY:- Construct validation has focused attention on the role of psychological theory in test construction and on the need to formulate hypothesis that can be proved or disproved in the validation process. “The construct validity of a test is the extent to which the test may be said to measure a theoretical construct or trait”.

3.CONTENT VALIDITY:- Content validity involve essentially the systematic examination of the test content to determine whether it covers a representative sample of behaviour domain to be measured. This validity procedures commonly used in tests designed to measure how well the individual has mastered a specific skill or course of study. It might be seem that mere inspection of the content of the test should suffice to establish its validity for such a purpose.