The Washington Group (WG) question sets were developed for use in censuses and surveys according to the Fundamental Principles of Official Statistics.
The questions reflect advances in the conceptualization of disability and use the World Health Organization’s International Classification of Functioning, Disability, and Health (ICF) as a conceptual model. The focus is on functioning in basic, universal activities in contrast to approaches that are based on a medical model which focus on impairments to bodily functions or structures.
By focusing data collection on those who have difficulty in carrying out a few basic, universal activities, the WG seeks to identify those who would be at greater risk than the general population of social exclusion (for example not able to access education or employment) if their environment was unaccommodating.
The WG questions sets are designed to provide comparable data cross-nationally for populations living in a variety of cultures with varying economic resources.
Using data derived from the WG Short Set of Questions (WG-SS) in conjunction with data from other questions on a census (e.g., access to education or employment), it is possible to compare the actual level of participation of the population at higher risk with those not experiencing similar functional difficulties. Observed differences in levels or degree of participation reflect the need for accommodation to equalize opportunities for full inclusion. This approach to disability is a central tenet of the UN Convention on the Rights of Persons with Disabilities.
The questions cover six functional domains: seeing, hearing, walking, cognition, self-care, and communication. Each question has four response categories: (1) No, no difficulty, (2) Yes, some difficulty, (3) Yes, a lot of difficulty and (4) Cannot do it at all. Scaled responses begin to describe the continuum of functioning from mild to severe.
The six domains will identify the majority of persons with disability – but not all. Multiple disability scenarios can be described depending on the domain(s) of interest and the choice of severity cut-off. There is more than one way to capture disability through the application of this set of core questions; resulting in not one but several possible prevalence estimates.
The WG has developed a methodology for testing the questions both cognitively and in the field. This ensures the questions are being interpreted consistently across languages and countries and are capturing the data they are intended to capture. Cognitive and field testing have shown WG questions produce internationally comparable data.