Scores on psychological tests are most commonly interpreted by reference to norms ; which represent the test performance of the standardized sample. The norms are empirically established by determining what person’s in a representative group actually do on the test. Any individual raw score is then reffered to the distribution of scores obtained by the standard sample, to discover where that person fall in that distribution.
Individual Test Score Is Interpreted In Two Ways:- Norm Referencing:- The first way is to compare an examinee’s test score with the score of a specific group of examinees on that test. This process is known as norm referencing. Criterion Referencing:- The second way of interpreting a test score is to establish an external criterion and compare the examinee’s test score with it. This process is known as criterion referenced test, there is a fixed performance criterion.
Types of Norms:- • Age equivalent norms:- These norms are defined as the average performance of a representative sample of a certain age level on the measure of a certain trait or ability. Age norms are most suited to those traits which increase systematically with age. like Intelligence.
Grade Equivalent Norms:- These norms are defined as the average performance of a representative sample of a certain grade or class. These are found by computing the mean raw score obtained by childern in each grade. Like if the average number of problem solved correctly on an arithmatic test by a fourth graders in the standard sample is 23 than a raw score of 23 corresponding to a grade equivalent of fourth.
Within Group Norms:- In within group norms there are two types of norms. • Percentiles • Standard score Norms
Percentiles:- Percentiles are expressed in terms of the percentage of persons in the standardization sample. A percentile indicate the individual relative position in the standardization sample. Percentiles are different from percentage scores; the percentage scores are raw scores, which expressed in terms of percentage of correct items and percentiles are derived scores, which expressed in terms of percentage of a person.
Standard Score Norms:- Standard scores express the individual’s distance from the mean in terms of the standard deviation of the distribution. Standard score is a derived score which has a fix mean and fixed standard deviation. There are several types of standard scores such as z score(also known as sigma scores), T score, Sten score, Stanine score, deviation IQ etc.