Box 1: Varying concepts of disability affecting disability data Traditionally – and in many administrative data collection systems – disability has been approached as a binary ‘yes’ or ‘no’ matter (i.e. when answering the question ‘do you have a disability?’). This leads to significant under-reporting of disability prevalence due to stigma and differing understandings of what is understood as a disability. By contrast, universal models of disability – such as the model underpinning the WHO’s International Classification of Disability (ICF) – approach disability as a continuum, in line with the Convention on the Rights of Persons with Disabilities, which stresses that ‘disability results from the interaction between persons with impairments and attitudinal and environmental barriers that hinder their full and effective participation in society on an equal basis with others’.