Designing an IQ test

• An individual’s performance is compared with the performance of a reference group, known as the normative or standardisation sample.
• It is useful when wanting to know how good someone is relative to others.

How well a person performs on the kinds of task found in the test, or how likely the person is in everyday life to show the kind of behaviour demonstrated in the test.

• Finds out whether someone has achieved a required level of performance (the criterion), with an emphasis on predicting behaviour outside the testing situation
• Useful if wanting to know whether someone is competent for e.g. a job.

Ordinal scales: Behavioural sequences. Stages of development are ordered (e.g. from foetal posture, to sitting and crawling, to walking etc.), and the individual is assessed in terms of these milestones 

Ordinal scales: Theory-based. e.g. Piaget’s proposed stages of development.

• Percentiles 
• Standard Scores: One form of the use of a standard score is the Z score.
• This expresses someone’s performance in terms of how many standard deviations their performance is away from the normative group’s mean. It has the advantage of getting away from the inequality of percentile units.
• Normalised standard scores: this is used when the normative distribution departs from normality. One finds the number of people scoring within a particular range, and converts these to Z scores of the normal distribution.

• Used to ascettaion if someone has reached a certain level of skill in occupational testing 
• Doesn't matter how well they stack up with others, they just have to pass a threshold

• If people are just measured against each other in a school year then a decline in educational standards could go unnoticed
• Norm referenced could also place minority groups at an unfair disadvantage