Characteristics of a Good Measuring Instrument

VALIDITY : First and foremost a test must be valid i.e. must measure what it claim to measure. It refers to validity of assessment. If a test is valid it is almost reliable.

MEASUREMENT OF VALIDITY : There are three ways to measure validity.

Validity refers to the degree to which a study accurately reflects or assesses the specific concept that the researcher is attempting to measure.

CRITERION VALIDITY : Criterion related validity, also referred to as instrumental validity, is used to demonstrate the accuracy of a measure or procedure by comparing it with another measure or procedure which has been demonstrated to be valid.
For example, imagine a hands-on driving test has been shown to be an accurate test of driving skills. By comparing the scores on the written driving test with the scores from the hands-on driving test, the written test can be validated by using a criterion related strategy in which the hands-on driving test is compared to the written test.


CONSTRUCT VALIDITY : Construct validity seeks agreement between a theoretical concept and a specific measuring device or procedure. For example, a researcher inventing a new IQ test might spend a great deal of time attempting to "define" intelligence in order to reach an acceptable level of construct validity.


CONTENT VALIDITY : Content validity is illustrated using the following examples: Researchers aim to study mathematical learning and create a survey to test for mathematical skill. If these researchers only tested for multiplication and then drew conclusions from that survey, their study would not show content validity because it excludes other mathematical functions.