Construct Validation of the Supports Intensity Scale - Children and Adult Versions: An Application of a Pseudo Multitrait-Multimethod Approach.

Seo et al. (2016) checked if the Supports Intensity Scale really measures support needs. They used a fancy stats trick called a pseudo multitrait-multimethod model. This let them see if scores show true support needs instead of just test noise.

They tested both the adult form (SIS-A) and the child form (SIS-C) in people with intellectual disability.

Trait variance beat method variance. In plain words, the scales mostly measured real support needs, not random error. Both forms passed the convergent-validity test.

Patterns were not identical: adult and child forms showed slightly different score structures, so keep age in mind when you pick one.

Wehmeyer et al. (2009) came first. They showed SIS scores predict high funding needs in adults with ID. Hyojeong adds proof that the scores are internally solid, not just predictive.

Arnkelsson et al. (2016) extends the story. They found the SIS also works for adults with motor disability and explained even more score variance. Together, the papers say the tool is robust across diagnoses.

MacLean et al. (2011) sounds negative: the WAIS-III structure fails in adults with ID. That warning makes Hyojeong’s good SIS fit more important. When IQ tests mis-fit, switch to a support-needs lens instead.

You can trust SIS-A and SIS-C scores when you write ISP goals or justify hours. The scales capture real support needs, not fluff. Still, treat adult and child results a bit differently, and remember the tool now has backing beyond just ID.