Adaptive Testing

Types

Alfred Binet’s IQ (intelligence quotient) test, first developed in the early 1900s, had all of the characteristics of an adaptive test: (a) the item bank for Binet’s IQ test (later known as the Stanford-Binet IQ test) was normed on children and young adults by placing items into levels based on the age at which the items were answered correctly by about 50% of a given age grouping; (b) Binet’s test began for each examinee based on the information that the psychologist had about the examinee obtained from a teacher or a parent; (c) items were administered and scored immediately by the examiner; (d) at the end of each age level, the examiner chose the next level to be administered based on the proportion correct; and (e) the test ended when the examiner had identified a ceiling level at which all items were answered correctly and a basal level at which all items were answered incorrectly. Between these two levels the examiner will have located the range of effective measurement for each examinee. The procedure is efficient as well as effective because it administers only items in that part of the larger item bank that are necessary to measure each individual.

Computerized adaptive tests extend the basic ideas of adaptive testing and generally combine them for maximum efficiency and effectiveness. Partially adaptive CATs are similar in some respects to the Binet adaptive tests and include CATs that are based on item banks that are stratified by levels of item difficulty or CATs that use structured item banks and administer items in stages. The latter are referred to as multistage tests (MSTs). Multistage tests administer a small set of items (sometimes called a testlet), score that set of items, and then select a new set of items based on the score from the first set. Multistage tests typically are based on a predesigned structure of testlets and have several stages of testlets arranged in a branching structure. Movement from one stage to the next is based on an examinee’s score on the previous stages. The number of stages is predetermined, as is the number of items in each testlet.

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