Examining the validity of the use of ratio IQs in psychological assessments.

This study looked at whether ratio IQ scores (a backup scoring method used when children can't complete standard IQ tests) are accurate. Looking at over 16,000 autistic children, researchers found that ratio IQ scores were often different from standard IQ scores, especially for younger children and those with very high or very low abilities. This suggests that this common testing practice may not give accurate results.

This large-scale study examined the validity of ratio IQ (RIQ) scores, commonly used when children cannot complete standard intelligence tests. Analyzing data from 16,751 autistic participants aged 2-18 across five intelligence tests, researchers found significant discrepancies between standard full-scale IQ (FSIQ) and RIQ scores. The differences were particularly pronounced for children at the extremes of IQ distribution and varied by age, with RIQ overestimating abilities in younger children but underestimating in older children. These findings question the widespread clinical practice of using RIQ as a proxy for standard IQ, especially for individuals with intellectual disabilities or giftedness where RIQ is most commonly employed.

Clinicians should exercise caution when using ratio IQ scores, particularly for individuals at IQ extremes and when making age-based comparisons. Standard protocols may need revision to ensure accurate cognitive assessment in autism. Alternative approaches to handling incomplete IQ assessments should be considered.

Study focused primarily on autistic participants, though secondary analyses included typically developing children. The research examined discrepancies but did not establish which scoring method provides more accurate representation of cognitive abilities. Methodological details about specific calculation procedures were not fully detailed in the abstract.

Intelligence tests are amongst the most used psychological assessments, both in research and clinical settings. To avoid missing data points, for participants who cannot complete Intelligence tests normed for their age, ratio IQ scores (RIQ) are routinely computed and used as a proxy of IQ. Here, we use the case of autism to examine the validity of this widely used, yet never scientifically validated, practice. We examine the differences between standard full-scale IQ (FSIQ) and RIQ.

Data was extracted from four databases in which age, FSIQ scores and subtests raw scores (from which RIQ scores could be calculated) were available for 16,751 autistic participants between 2 and 18 years old. The Intelligence tests included were the MSEL (N = 12,033), DAS-II early years (N = 1270), DAS-II school age (N = 2848), WISC-IV (N = 471) and WISC-V (N = 129). RIQs were computed for each participant as well as the discrepancy (DSC) between RIQ and FSIQ. We performed a multiple linear regression model to assess the effects of age and FSIQ on DSC for each IQ test.

Participants at the extremes of the FSIQ distribution tended to have a greater DSC than participants with average FSIQ. Furthermore, age significantly predicted the DSC, with RIQ superior to FSIQ for younger participants while the opposite was found for older participants. Similar results were found in secondary analyses including typically developing children. These results question the validity of the RIQ as an alternative scoring method, especially for individuals at the extremes of the normal distribution, for whom RIQs are most often employed.