The Interaction with Disabled Persons scale: revisiting its internal consistency and factor structure, and examining item-level properties.
Trash the long IDP—only its five-item Discomfort subscale gives reliable scores.
01Research in Context
What this study did
Teresa and her team looked again at a popular attitude survey called the Interaction with Disabled Persons scale (IDP).
They ran fresh stats on the old six-factor structure to see which parts still hold up.
The sample was not described, but the work is a psychometric re-analysis, not a new data collection.
What they found
Only five items that measure personal discomfort passed reliability tests.
The other five supposed factors fell apart, so the full 30-item scale is not sound.
If you want a quick read on how uneasy someone feels around people with disabilities, use just those five discomfort questions.
How this fits with other research
Werner et al. (2012) checked 24 stigma tools and found most lack solid theory; Teresa’s 2009 critique of the IDP is one of the weak tools they flag.
van Timmeren et al. (2016) also reran factor models on ID assessments and likewise showed that simpler, cleaner dimensions predict better than old, bulky ones.
Christopher et al. (1991) warned that factor structures can shift with age and ability level; Teresa’s work echoes that warning for attitude scales.
Why it matters
Before you give staff or students any attitude survey, flip to the stats appendix. If the factor list looks like the full IDP, pick a different tool or trim to the five discomfort items. You will save time and get data you can actually trust.
Want CEUs on This Topic?
The ABA Clubhouse has 60+ free CEUs — live every Wednesday. Ethics, supervision & clinical topics.
Join Free →Open your survey folder and delete any full IDP forms; replace with the five discomfort items if you need an attitude probe.
02At a glance
03Original abstract
The Interaction with Disabled Persons scale (IDP) has been used in research into baseline attitudes and to evaluate whether a shift in attitudes towards people with developmental disabilities has occurred following some form of intervention. This research has been conducted on the assumption that the IDP measures attitudes as a multidimensional construct and has good internal consistency. Such assumptions about the IDP appear flawed, particularly in light of failures to replicate its underlying factor structure. The aim of this study was to evaluate the construct validity and dimensionality of the IDP. This study used a prospective survey approach. Participants were recruited from first and second year undergraduate university students enrolled in health sciences, occupational therapy, physiotherapy, community and emergency health, nursing, and combined degrees of nursing and midwifery, and health sciences and social work at a large Australian university (n=373). Students completed the IDP, a 20-item self-report scale of attitudes towards people with disabilities. The IDP data were analysed using a combination of factor analysis (Classical Test Theory approach) and Rasch analysis (Item Response Theory approach). The results indicated that the original IDP 6-factor solution was not supported. Instead, one factor consisting of five IDP items (9, 11, 12, 17, and 18) labelled Discomfort met the four criteria for empirical validation of test quality: interval level scaling (scalability), unidimensionality, lacked of DIF across the two participant groups and data collection occasions, and hierarchical ordering. Researchers should consider using the Discomfort subscale of the IDP in future attitude research since it exhibits sound measurement properties.
Research in developmental disabilities, 2009 · doi:10.1016/j.ridd.2009.07.010