not be any variation in the scores obtained by the students on the two occasions. For this, we can compute test-retest reliability, which indicates the temporal stability (or stability of the test scores over time). It is computed by finding out co-efficient of correlation between the two sets of scores on the same set of persons. Another kind of test reliability is called split-half reliability.
It gives an indication about the degree of internal consistency of the test. This is based on the assumption that items of a test if they are from the same domain should correlate with each other. If they are from different domains, e.g., are apples and oranges, then they would not. For finding out internal consistency, the test is divided into two equal halves employing odd- even method (items , , ,— in one group and items , , ,— in another group) and correlation is computed between the scores of odd and even items.
For a test to be usable, it should also be valid. Validity refers to the question : “Does the test measure what it claims to measure”? For example, if you have constructed a test of mathematics achievement, whether the test is measuring mathematical achievement or for example, language proficiency. Finally, a test becomes a standardised test when norms are developed for the test.
As mentioned earlier, norm is the normal or average performance of the group. The test is administered on a large number of students. Their average performance standards are set based on their age, sex, place of residence, etc. This helps us in comparing the performance of an individual student with others of the same group.
It also helps in interpreting individuals’ score obtained on a test. Types of Tests Psychological tests are classified on the basis of their language, mode of administration, and difficulty level. Depending upon the language, we have verbal , non-verbal , and performance tests. Literacy is required for taking verbal tests as the items have to be written in some language.
In non-verbal tests, items are made of symbols or pictures. Performance tests require movement of objects