The Definition and Measurement of Disability: The Work of the Washington Group

1. The Definition and Measurement of Disability: The Work of the Washington Group Jennifer Madans Associate Director for Science US National Center for Health Statistics and The UN Washington Group November 9, 2006

2. The Washington Group on Disability Statistics • In 2001, the UN International Seminar on the Measurement of Disability recommended the development of principles and standards for global indicators of disability to be used in censuses • The Washington Group was formed under the aegis of the UN Statistical Commission to • Foster international cooperation in the area of health and disability statistics • Develop disability measures suitable for censuses and surveys • Untangle the web of confusing and conflicting disability estimates

3. Current Problem • Currently national censuses in developing countries use one of three types of questions that provide widely differing estimates of national prevalence of disability: • The three types of questions include • A. Generic question about the presence of a condition • B. Generic questions about the presence in the household of a person with a disability followed by a list of impairments • C. Checklist of impairments

4. Reported Disability Prevalence Varies Widely Bangladesh 0.8 Niger 1.3 Philippines 1.3 Colombia 1.8 Egypt 4.4 Germany 8.4 United States 15.0 Australia 18.0 Source: UN Statistics Division

5. Washington Group: Objectives • Develop a small set/s of disability questions that could be used on Censuses/surveys • Recommend extended set/s of items to measure disability as components of population surveys / supplements • Address methodological issues associated with disability measurement

6. Preliminary work to meet objectives • Clarify the purpose of data collection in order to identify appropriate measures • Understand choices being made when time, expenses and respondent burden limit number of questions

7. Moving from Concept to Definition to Measurement: The Conceptual Model ICF selected as the conceptual model: • Common point of reference • Common vocabulary • Does not provide an operational definition or a way to measure the concepts

8. Moving from Concept to Definition to Measurement: The Definitional Paradox • There is no single operational definition of disability • Different operational definitions lead to different estimates • The question you are trying to answer (the purpose) will determine which definition to use • Need to understand the choices that are being made when a purpose and a definition are chosen • Need to understand the choices that are being made when time, expenses and respondent burden limit number of questions

9. Purpose of Data Collection 3 major classes of purposes at aggregate level • Service Provision • Monitoring functioning in the population • Assess equalization of opportunities 2 criteria for selection of a purpose • Relevance—particularly for policy makers and program officials • Feasibility

10. Purpose: Service provision • Seeks to identify those with specific needs, usually the most serious problems • Requires detailed information about the person and the environment • Influenced by the organization and structure of service organizations within a particular culture

11. Purpose: Monitoring functioning in the population • Seeks to identify all those with activity or participation limitation • Response comparability problematic since participation is culturally and environmentally determined Population reporting work limitation

12. Purpose: Equalization of opportunities • Seeks to identify all those at greater risk than the general population for limitations in activity or participation • Disability as a demographic % Employed

13. Applying criteria to select purpose • Service provision: • Level of detail necessary not feasible in a census format • Nature of service provision varies across cultures • Monitoring functioning: • Response comparability problematic since participation is culturally and environmentally determined • Assessing equalization of opportunities: • If we conceive of disability toward the most basic elements of activity, without tying it to participation, we limit the number / types of questions thus enhancing feasibility

14. Moving from Concept to Definition to Measurement: Measurement of equalization of opportunities • Locate the definition of disability at the most basic level of activity/participation in core domains • This level is associated with the ability or inability to carry out basic bodily operations at the level of the whole person (i.e. walking, climbing stairs, lifting packages, seeing a friend across the room) • Connection between disability and participation can be made during data analysis

15. Locating Risk in the ICF Model Health Condition ACTIVITY ? Body Functions & Structure Participation Source: ICF, WHO, 2001 Environmental Factors Personal Factors

16. Criteria for inclusion of domains • Cross cultural comparability • Suitability for self-report • Parsimony • Validity across various methodological modes

17. WG Questions for Censuses Core Questions: Do you have difficulty seeing even if wearing glasses? Do you have difficulty hearing even if using a hearing aid? Do you have difficulty walking or climbing stairs? Do you have difficulty remembering or concentrating? Additional Questions: Do you have difficulty with self-care, such as washing all over or dressing? Because of a physical, mental, or emotional health condition, do you have difficulty communicating (for example understanding others or others understanding you)? Response categories: No - no difficulty; Yes – some difficulty; Yes – a lot of difficulty; Cannot do at all

18. Objectives • Identify persons with similar types and degree of limitations in basic activities regardless of nationality or culture • Represent the majority (but not all) persons with limitations in basic activities in any one nation • Represent the most commonly occurring limitations in basic activities within any country • Capture persons with similar problems across countries

19. Intended use of data • Development of a demographic means of understanding disability: Can compare persons with and without disability on levels of participation in employment, education, or family life to see if persons with disability have achieved social inclusion • Monitor effectiveness of programs / policies to promote full participation can be monitored • Monitor prevalence trends for persons with limitations in specific basic activity domains

20. Work on Extended Measures • The WG is reviewing disability questions from current instruments in order to form various recommended modules for different purposes • Going in-depth on the same 6 domains as covered by the census questions • Adding additional domains of functioning such as learning (especially for children), social interactions, and some of the other more complex activities listed in the ICF A/P classification. • Asking about participation • Asking questions on environmental factors.