3.3 Psychological tests
The most commonly used psychological tests, such as intelligence tests and personality tests, are highly structured forms of self-report where participants have to solve problems or choose from fixed alternatives on a questionnaire. Researchers then work out a score for each participant that gives information about their intelligence or personality. These tests are different from ordinary questionnaires in the way they are constructed and pre-tested. They are tried out on large numbers of people before being used as research or diagnostic tools. This gives a picture of how the test scores are distributed across the population for which the test is designed. It is, therefore, possible to compare a particular individual's test scores with the average from the population and to make statistical comparisons between different groups.