Monday, April 30, 2012

IAP AP101 Report # 13: Problems with the 1960 and 1986 Stanford-Binet IQ Scores in Atkins MR/ID Death Penalty Cases

Often in Atkins MR/ID death penalty cases historical and contemporary IQ scores are available for review by psychological experts.  In many cases these scores vary markedly.  The courts frequently wrestle with the issue of determining what the best estimate is of the person’s general intelligence.  A review of many Atkins cases often reveals frequent mention of two “gold standard” IQ tests in reports or testimony—namely, the Stanford-Binet and the Wechsler series.

The purpose of this working paper is to alert psychologists and the courts to two little known (but extremely important) dents in the gold standard status of two versions of the Stanford-Binet—the 1960 SB and the 1986 SB IV. If a Flynn effect adjustment is made to scores from a 1960 SB, the norm date used to calculate the magnitude of the Flynn effect should be 1932…not 1960.  If SB IV scores exist in an individual’s records, experts providing opinions regarding the individual’s general level of intelligence should consider: (a) eliminating the score from consideration, (b) not give the score great weight in formulating an opinion, or (c) at a minimum, provide qualifying statements regarding the validity of the SB IV score as required by the Joint Test Standards.

IAP Applied Psychometrics 101 Report # 13 can be downloaded by clicking here.