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Beyond the floor effect on the W echsler I ntelligence S cale for C hildren – 4th E d. ( WISC ‐ IV ): calculating IQ and I ndexes of subjects presenting a floored pattern of results
Author(s) -
Orsini A.,
Pezzuti L.,
Hulbert S.
Publication year - 2015
Publication title -
journal of intellectual disability research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.941
H-Index - 104
eISSN - 1365-2788
pISSN - 0964-2633
DOI - 10.1111/jir.12150
Subject(s) - raw score , wechsler intelligence scale for children , intelligence quotient , wechsler adult intelligence scale , intellectual disability , psychology , scale (ratio) , developmental psychology , raw data , psychiatry , cognition , statistics , mathematics , physics , quantum mechanics
Background It is now widely known that children with severe intellectual disability show a ‘floor effect’ on the W echsler scales. This effect emerges because the practice of transforming raw scores into scaled scores eliminates any variability present in participants with low intellectual ability and because intelligence quotient ( IQ ) scores are limited insofar as they do not measure scores lower than 40. Method Following H essl et al .'s results, the present authors propose a method for the computation of the Wechsler Intelligence Scale for Children – 4th Ed. (WISC‐IV)'s IQ and I ndexes in intellectually disabled participants affected by a floored pattern of results. The I talian standardization sample ( n = 2200) for the WISC ‐ IV was used. The method presented in this study highlights the limits of the ‘floor effect’ of the WISC ‐ IV in children with serious intellectual disability who present a profile with weighted scores of 1 in all the subtests despite some variability in the raw scores. Results Such method eliminates the floor effect of the scale and therefore makes it possible to analyse the strengths and weaknesses of the WISC ‐ IV 's I ndexes in these participants. Conclusions The Authors reflect on clinical utility of this method and on the meaning of raw score of 0 on subtest.