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Distribution & Use of IQ Scores

Normal distribution of IQ scores

Mental retardation: IQ scores:
 
 Borderline mentally retarded: 50 - 75
 Mild/moderately mentally retarded: 35 - 50
 Severe/profoundly mentally retarded: 20 - 40

Mental retardation causes:
 
    1. Organic retardation
        2. Cultural-familial retardation

Vast majority (95%) of IQ scores: 70 to 130

•  IQ scores & academic achievement - medium strength correlation
•  IQ scores & job performance - low to medium strength correlation

Gifted IQ scores: superior 130 - 145; gifted 145+

•  Binet's two warnings on potential problems of IQ Testing:
 
    1. Intelligence tests do not measure innate abilities or natural intelligence.
        2. Intelligence tests, by themselves, should not be used to label people.