Background: Support staff of adults with intellectual disability (ID) play an important role in promoting independence in home and community settings. However, little is known about the types of behaviours staff should use to promote independence and instruments that assess such behaviour do not yet exist. The aim of this study was therefore to develop and initially validate a reliable questionnaire that measures the degree to which support staff display behaviours that promote independence in people with ID.

Method: The Leiden Independence Questionnaire for Support Staff (LIQSS) was constructed to measure the extent to which support staff promote independence in people with ID. The LIQSS was completed by 142 staff members working with people with ID. For the psychometric evaluation of the LIQSS, a principal component analysis was performed with an oblique rotation in all items. Next, the principal component analysis was performed with a forced three-component extraction, and three sub-scales were computed. To assess internal consistency, Cronbach's α was calculated for each of the sub-scales.

Results: The LIQSS was found to consist of three internally consistent (Cronbach's α was respectively 0.92, 0.79 and 0.76) and meaningful components: (1) communication, agreements and coordination; (2) positive encouragement and tailoring; and (3) supporting independent performance. The final 22 items had factor loadings between 0.44 and 0.91 on their corresponding component and a minimal difference in loading to the other factors of 0.20.

Conclusions: The LIQSS appears to be an instrument with positive face validity and reliability (internal consistency) that assesses the degree to which support staff promote independence in people with ID. To increase the instrument's value for both scientific research and clinical practice, studies should focus on the further validation of the LIQSS.

Keywords: independence; intellectual disabilities; questionnaire; self-management; support staff.

© 2018 The Authors. Journal of Intellectual Disability Research published by MENCAP and International Association of the Scientific Study of Intellectual and Developmental Disibilities and John Wiley & Sons Ltd.