How can one measure intelligence? Producing a good intelligence test Individual and group intelligence tests The nature of intelligence The measurement of intelligence Psychometrics

Test: “...a standardized instrument, consisting of items, for obtaining a reliable sample of some valid aspect of a person’s behavior (e.g. thinking and reasoning abilities).”

Test-retest reliability Alternate-forms reliability Split-half reliability Inter-rater reliability Criterion validity Content validity Construct validity

Hypothetical item analysis for a particular multiple-choice question Students with different overall performance Proportion getting item correct

Hypothetical item analysis for a particular IQ test question 1 0.9 0.8 0.7 0.6 Proportion getting item correct 0.5 0.4 0.3 0.2 0.1 5 6 7 8 9 Age

The Stanford-Binet version of IQ: The WAIS version of IQ:

Standardized scoring of the WAIS IQ tests: (Assumption of normal distribution of IQ scores) Mean = 100 +1.00 -1.00 Z Standard Deviation = 15 IQ 70 100 130 -2.00 +2.00

Correlation Matrix of Five Subtests of an IQ Test 1 2 3 4 5 6 1 2 3 4 5 6 .39 .30 .62 .35 .40 .59 .45 .41 .55 .64 .28 .63 .34 .60 .38