Person Ability Scores as an Alternative to Norm-Referenced Scores as Outcome Measures in Studies of Neurodevelopmental Disorders.

The data were used for illustration and not to test hypotheses relevant to the original studies. The samples were small, with 29 participants in the Vineland-3 illustration and 26 in the Differential Ability Scale-II illustration. The estimates of change were imprecise because the samples were small. The report could not compare groups, only change within individuals. The Vineland-3 Motor domain was excluded because norm-referenced scores are not available for participants older than 9 years. Ability scores are not directly interpretable without knowing what change is meaningful. Ability scores are usually available only at subscale level, not for composite constructs. Ability scores are unitless and specific to a test version, so scores from different versions cannot be compared. If a test lacks low-level items, no score type may be sensitive enough.

Do not read this as proof that ability scores are clinically superior for every patient or that they show a treatment worked. The report used small illustrative datasets and did not test group differences, meaningful change, or clinical outcomes.