In order to do so, psychological measures must meet certain criteria to be considered objective measures. A complete discussion of psychometric theory is beyond the scope of this brief exploration, but the following characteristics are important to consider. Norms are used as a reference against which psychological test data is interpreted. They consist of the test performance of a standardization sample that is reflective of the general population under consideration. Without normative data, the information obtained regarding a person is meaningless.
Norms provide a means of assessing a person's relative standing in comparison to others.
They include comparing IQ and grade equivalence. Within-group norms are used to evaluate a person's performance in terms of a similar comparison group. For example, comparing a child's performance to others his or her age, or comparing a schizophrenic patient to other schizophrenics. Reliability refers to the consistency of scores obtained by a person when re-examined. The degree to which a test is reliable defines the accuracy with which it assesses the person.