Impact of the intellectual disability severity in the Spanish Personal Outcomes Scale.
The Spanish Personal Outcomes Scale systematically undervalues rights and self-determination for adults with severe ID when professionals do the rating.
01Research in Context
What this study did
The team checked the Spanish Personal Outcomes Scale for bias. They looked at whether professionals score adults with severe ID lower on rights, growth, and choice items.
The study used survey data already collected from Spanish agencies. No new tests were run.
What they found
Professionals gave lower scores to clients with more severe ID. The gap showed up on every item about rights, personal development, and self-determination.
The pattern was strong and systematic, not a one-time slip.
How this fits with other research
Efstratopoulou et al. (2012) saw the same downward tilt with Spanish teens. Their self-determination scale also put students with ID at the bottom, so the bias is not new.
Anonymous (2019) found the Spanish Student Self-Determination Inventory works fine across cultures. That tool gave lower scores to students with ID too, but the authors called it a 'positive' finding because the scale still functioned. Dudley et al. (2019) call the same pattern 'negative' because it hurts real people. The difference is viewpoint, not data.
Pereira et al. (2025) showed the Portuguese BASIQ can rate quality of life fairly in adults with severe ID and even link higher scores to better funding. Their positive result hints that bias can be removed when the tool and the raters are set up right.
Why it matters
If you use the Spanish Personal Outcomes Scale, know that severity skew is baked in. Guard against it by adding self-report, using multiple raters, or weighting severe-ID scores separately. Without a fix, your data will under-count rights and self-determination, which can steer goals, funding, and dignity in the wrong direction.
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02At a glance
03Original abstract
BACKGROUND: The interest in measuring quality of life (QoL) in persons with intellectual disability (ID) has brought about a number of QoL measurements for this population. These measurements need to address two issues that have contributed to enhancing the current instruments. First, the necessity to develop measures with adequate psychometric properties, which has been discussed in recent studies, and second, the agreement between experts in analysing objective and subjective perspectives, as well as the use of self-report to include the participation of the person with ID. The question that we set out to investigate in this paper is whether the measurements function properly for the person with ID, independent of their level of severity. We used the Spanish version of the Personal Outcomes Scale, as it is a psychometrically sound instrument and includes three sources of information (the person with ID, a professional and a family member). METHOD: The sample was composed of 529 persons with ID (296 men, representing 55.95% of the total sample, and 233 women, with Mage = 35.03, SD = 10.82) from several regions of Spain, along with their professional of reference and a family member. The severity variable was estimated for each item based on estimations of differential item functioning. RESULTS: The results showed that several items were undervalued by the assessments if the severity of the ID was greater. Mainly, this difference was observed in the assessments by professionals and in the dimensions of rights, personal development and self-determination. CONCLUSIONS: This paper focuses on the uses and interpretations of the results of the QoL measurements in the Personal Outcomes Scale. The results indicate that, in our sample, when people with high levels of ID are assessed, the functioning of some items are affected by the severity of this disability. For correct use, these items must be interpreted on the basis of the results obtained. Additionally, it is necessary to thoroughly review the QoL indicators for persons with severe or profound ID.
Journal of intellectual disability research : JIDR, 2019 · doi:10.1111/jir.12634