Person Ability Scores as an Alternative to Norm-Referenced Scores as Outcome Measures in Studies of Neurodevelopmental Disorders
Open accessAbstract
Although norm-referenced scores are essential to the identification of disability, they possess several features which affect their sensitivity to change. Norm-referenced scores often decrease over time among people with neurodevelopmental disorders who exhibit slower-than-average increases in ability. Further, the reliability of norm-referenced scores is lower at the tails of the distribution, resulting in floor effects and increased measurement error for people with neurodevelopmental disorders. In contrast, the person ability scores generated during the process of constructing a standardized test with item response theory are designed to assess change. We illustrate these limitations of norm-referenced scores, and relative advantages of ability scores, using data from studies of autism spectrum disorder and creatine transporter deficiency.
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The NIHTB-CB provides uncorrected standard scores that measure absolute performance and are argued to be a more appropriate metric in intellectual disability.
“However, the NIHTB-CB also provides uncorrected standard scores, serving as a metric more akin to a person ability score, that measure absolute performance and are argued to be a more appropriate metric in ID (Farmer et al., 2020).”
From NIH Toolbox Cognition Battery Feasibility in Individuals With Williams Syndrome (2022) · cites this paper as Farmer et al., 2020
The Introduction (page unavailable) distinguishes person ability scores, which quantify ability, from norm-referenced standard scores, which do not convey absolute ability. The Discussion (page unavailable) argues that ability scores can be a useful alternative for studies of neurodevelopmental disorders. The paper does not establish that the NIHTB-CB provides uncorrected standard scores or that those particular scores measure absolute performance. (LLM, conf=0.85)
Experimental — accuracy not yet measuredIn individuals with ID, age-corrected standard scores often decrease over time even though their ability may have actually improved, due to slower rate of increasing cognitive skills compared to same-aged peers.
“due to the slower rate of increasing cognitive skills in people with ID, compared to their same-aged peers, age-corrected standard scores often decrease over time in individuals with ID even though their ability may have actually improved (Farmer et al., 2020).”
From NIH Toolbox Cognition Battery Feasibility in Individuals With Williams Syndrome (2022) · cites this paper as Farmer et al., 2020
The Introduction explains that when children with neurodevelopmental disorders gain ability more slowly than their age peers, age-normed scores can obscure improvement and may even decline. It does not establish that scores often decline in individuals with intellectual disability specifically; the Results’ Differential Ability Scale-II illustration instead reports stable or modestly improved norm-referenced scores. (LLM, conf=0.86)
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Research works printed but not linked: 8
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- Elliott CD (2007a). Differential Ability Scales, Second Edition. San Antonio, TX: The Psychological Corporation.
- Elliott CD (2007b). Differential Ability Scales, Second Edition: Introductory and technical handbook. San Antonio, TX.: Psychological Corporation.
- Hessl D, Nguyen D, Green C, Chavez A, Tassone F, Hagerman R, … Hall S (2009). A solution to limitations of cognitive testing in children with intellectual disabilities: the case of fragile X syndrome. Journal of Neurodevelopmental Disorders, 1(1), 33– 45. Retrieved from 10.1007/s11689-008-9001-8. doi: 10.1007/s11689-008-9001-8 19865612 PMC2768415 · DOI · Paper page
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- van de Kamp JM, Betsalel OT, Mercimek-Mahmutoglu S, Abulhoul L, Grünewald S, Anselm I, … Salomons GS (2013). Phenotype and genotype in 101 males with X-linked creatine transporter deficiency. J Med Genet, 50(7), 463– 472. Retrieved from https://jmg.bmj.com/content/jmedgenet/50/7/463.full.pdf. doi: 10.1136/jmedgenet-2013-101658 23644449 · DOI · Paper page
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Singh, L. J., Gaye, F., Cole, A. M., Chan, E. S. M., & Kofler, M. J. (2022) · Neuropsychology · doi:10.1037/neu0000798 · Cited by 32 · see citing works
Chan, E. S. M., Gaye, F., Cole, A. M., Singh, L. J., & Kofler, M. J. (2023) · Neuropsychology · doi:10.1037/neu0000918 · Cited by 6 · see citing works
NIH Toolbox Cognition Battery Feasibility in Individuals With Williams Syndrome
Condy, E. E., Becker, L., Farmer, C., Kaat, A. J., Chlebowski, C., Kozel, B. A., & Thurm, A. (2022) · American Journal on Intellectual and Developmental Disabilities · doi:10.1352/1944-7558-127.6.473 · Cited by 6 · see citing works
Self-citation
- Authors
- Farmer, C. A., Kaat, A. J., Thurm, A., Anselm, I., Akshoomoff, N., Bennett, A., Berry, L., Bruchey, A., Barshop, B. A., Berry-Kravis, E., Bianconi, S., Cecil, K. M., Davis, R. J., Ficicioglu, C., Porter, F. D., Wainer, A., Goin-Kochel, R. P., Leonczyk, C., Guthrie, W., Koeberl, D., Love-Nichols, J., Mamak, E., Mercimek-Andrews, S., Thomas, R. P., Spiridigliozzi, G. A., Sullivan, N., Sutton, V. R., Udhnani, M. D., Waisbren, S. E., & Miller, J. S.
- Affiliations
- National Institute of Mental Health (US)
- Northwestern University (US)
- Boston Children's Hospital (US)
- University of California San Diego (US)
- Children's Hospital of Philadelphia (US)
- Baylor College of Medicine (US)
- Lumos Pharma (United States) (US)
- Elizabeth Berry-Kravis, Rush University
- Eunice Kennedy Shriver National Institute of Child Health and Human Development (US)
- University of Cincinnati (US)
- Rush University (US)
- Robin P. Goin-Kochel, Baylor College of Medicine
- Duke University (US)
- Hospital for Sick Children (CA)
- Saadet Mercimek Andrews, University of Toronto, The Hospital for Sick Children, ON
- University of Pennsylvania (US)
- ORCID
- Farmer, Cristan A.
- Kaat, Aaron J.
- Thurm, Audrey
- Anselm, Irina
- Akshoomoff, Natacha
- Bennett, Amanda
- Berry, Leandra
- Barshop, Bruce A.
- Bianconi, Simona
- Cecil, Kim M.
- Ficicioglu, Can
- Porter, Forbes D.
- Wainer, Allison
- Leonczyk, Caroline
- Koeberl, Dwight
- Love-Nichols, Jamie
- Thomas, Rebecca P.
- Spiridigliozzi, Gail A.
- Sullivan, Nancy
- Sutton, Vernon R.
- Udhnani, Manisha D.
- Waisbren, Susan E.
- Miller, Judith S.
- Venue
- American Journal on Intellectual and Developmental Disabilities
- Publisher
- Informa UK Limited
- Published
- 2020-11-01
- Volume
- 125
- Issue
- 6
- Pages
- 475-480
- ISSN
- 1944-7558 (ISSN-L)
- 1944-7515
- PMC
- PMC11485197
- OpenAlex
- W3101403824
- Cited by
- 62
- References
- 0
- Citations by year
- 2026: 7 · 2025: 12 · 2024: 8 · 2023: 11 · 2022: 18 · 2021: 4 · 2020: 2
- FWCI
- 5.56
- Type
- journal article
- Language
- en
- Open access
- green
- www.ncbi.nlm.nih.gov
- Locations
- American Journal on Intellectual and Developmental Disabilities (publishedVersion)
- PubMed (publishedVersion)
- PubMed Central (acceptedVersion)
- eScholarship (California Digital Library) (submittedVersion)
- Funders
- National Institutes of Health
- National Institute of Mental Health (ZICMH002961)
- Eunice Kennedy Shriver National Institute of Child Health and Human Development (ZIAHD008989)
- Topics
- Social Sciences › Decision Sciences › Management Science and Operations Research › Psychometric Methodologies and Testing
- Life Sciences › Neuroscience › Cognitive Neuroscience › Autism Spectrum Disorder Research
- Social Sciences › Psychology › Applied Psychology › Psychological Testing and Assessment
- Keywords
- outcome measures, neurodevelopmental disorders, autism spectrum disorder, creatine transporter deficiency, floor effect, measurement error, item response theory, standardized testing, disability identification, sensitivity to change
- MeSH terms
- Autism Spectrum Disorder, Child, Creatine, Humans, Neuropsychological Tests, Psychometrics, Outcome Assessment, Health Care, Brain Diseases, Metabolic, Inborn, X-Linked Intellectual Disability, Plasma Membrane Neurotransmitter Transport Proteins, Neurodevelopmental Disorders
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