Thursday, September 17, 2009

Why IQ test scores differ: Applied Psychometrics 101---IQ scoring errors (next report)

Is it possible for an individual evaluated for mental retardation (as part of an Atkins proceedings) to have an increased probability of facing execution depending on whom administers them an intelligence test?  Is it possible for an experienced psychological examiner to make a sufficient number of scoring errors that significantly change a person's IQ score from what it should be (if properly scored)?  Unfortunately, the answers are "yes." 

I learned this first hand when I reviewed the test record and scoring of a intelligence test (on which I'm a coauthor) in a Federal death penalty appeal hinging on the diagnosis of mental retardation.  I've since been locating research articles on the accuracy of IQ test scoring for novice and experienced psychological examiners.  The results are discouraging. 

The next AP101 report will address the issue of test scoring errors in intelligence testing, with a particular emphasis on implications for Atkins MR death penalty cases.  The report will include a summary of representative literature, a discussion of my findings in the recent case for which I was a consultant (presented in such a manner to not reveal the identity of the case or any individuals/agencies involved in the case), and recommendations to address the issue.

Stay tuned.

If you have not read the first report in the series, check it out.  AP101 101:  IQ Test Score Difference Series--#1 Understanding global IQ test correlations.

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