title: Intelligence is in the eye of the beholder: investigating repeated IQ measurements in forensic psychiatry.
abstract: BACKGROUND
  A stable assessment of cognition is of paramount importance for forensic psychiatric patients (FPP). The purpose of this study was to compare repeated measures of IQ scores in FPPs with and without intellectual disability.
  
  
  METHODS
  Repeated measurements of IQ scores in FPPs (n = 176) were collected. Differences between tests were computed, and each IQ score was categorized. Additionally, t-tests and regression analyses were performed.
  
  
  RESULTS
  Differences of 10 points or more were found in 66% of the cases comparing WAIS-III with RAVEN scores. Fisher's exact test revealed differences between two WAIS-III scores and the WAIS categories. The WAIS-III did not predict other IQs (WAIS or RAVEN) in participants with intellectual disability.
  
  
  CONCLUSIONS
  This study showed that stability or interchangeability of scores is lacking, especially in individuals with intellectual disability. Caution in interpreting IQ scores is therefore recommended, and the use of the unitary concept of IQ should be discouraged.
authors.affiliation: Knowledge Centre Forensic Psychiatric Care (KeFor) OPZC Rekem, Rekem, Belgium.
authors.forename: Petra
authors.initials: P
authors.lastname: Habets
authors.forename: Inge
authors.initials: I
authors.lastname: Jeandarme
authors.forename: Kasia
authors.initials: K
authors.lastname: Uzieblo
authors.forename: Karel
authors.initials: K
authors.lastname: Oei
authors.forename: Stefan
authors.initials: S
authors.lastname: Bogaerts
mesh_terms: D000328:Adult; D005260:Female; D005555:Forensic Psychiatry; D006760:Hospitalization; D006778:Hospitals, Psychiatric; D006801:Humans; D008607:Intellectual Disability / Q000175:diagnosis / Q000523:psychology*; D007360:Intelligence; D007361:Intelligence Tests / Q000592:standards; D008297:Male; D009426:Netherlands; D012044:Regression Analysis
keywords: Groninger Intelligence Test; IQ; RAVEN; WAIS; cognitive ability; intelligence tests; psychometrics; repeated measures; stability