User Note - Washington Group on Disability Statistics Measures
The Washington Group Initiative
The Washington Group on Disability Statistics (WG) is a United Nations Statistical Commission City Group that formed in 2001 for, according to their website, "the promotion and coordination of international cooperation in generating statistics on disability suitable for censuses and national surveys." The WG is made up of national statistical agencies, UN agencies (e.g., UNICEF, ILO, World Bank), bilateral aid agencies (e.g., USAID), nongovernmental organizations, organizations representing people with disabilities, and researchers. The main objective of the WG is to provide basic information on disability that is comparable worldwide. For more information, please visit the Washington Group website.
Washington Group Disability Measures Included on the NHIS Questionnaire
The NHIS uses questions from the WG Extended Set on Functioning (WG-ES) for sample adults. The WG-ES is intended for use in national disability or health surveys that can support more detailed analyses of disability than, for example, censuses or labor force surveys could. The NHIS also includes the WG/UNICEF Child Functioning Module (CFM) for sample children ages 2 to 17. The CFM questions are split into two sets depending on the age of the sample child; one set is for children ages 2 to 4 and the other is for children ages 5 to 17.
The 2019 survey description states, "[The WG questions] focus on several domains of functioning that are likely to identify the majority of adults and children at risk of participation restrictions in an unaccommodating environment." They are intended to describe the functional status of adults and children across functional domains of seeing, hearing, mobility, communication, cognition, self-care, anxiety, and depression; for adults only, across functional domains of upper body functioning, pain, and fatigue; and for children only, across functional domains of dexterity, playing, learning, relationships, and kicking/biting/hitting others. The questions ask about the level of difficulty in basic domains of functioning and when used with other questions on the survey, can evaluate if adults and children with functional limitations are able to participate in everyday activities at levels similar to adults and children without functional limitations.
Analyzing WG Disability Measures
The NHIS provides three composite disability status indicators: one for sample adults age 18 and older, one for sample children ages 2-4, and one for sample children ages 5-17. These indicators identify adults and children who are at greater risk than the general population for experiencing restrictions in participation because of difficulties doing certain universal, basic actions. If a sample child or sample adult reported "a lot of difficulty" or "cannot do at all" for at least one question, they were classified as with disability.
In addition to the composite disability status indicators offered as part of NHIS, users can also tailor the data to the needs of their analysis and analyze disability measures from the WG individually, by domain, or across domains. Using the WG Short Set (WG-SS) or the WG-ES researchers can operationalize their own definition of disability by choosing to make dichotomous, categorical, or continuous variables that differ from the composite disability status indicators included in the NHIS.
Creating Dichotomous Disability Measures
To create a dichotomous measure with a more conservative threshold than those provided by the NHIS (i.e., a threshold that classifies fewer respondents as having a disability), users can set the cutoff so that only people who answered "cannot do this at all" for at least one question are identified as having a disability (compared to people who answered to "a lot of difficulty" or "cannot do at all" to at least one question for the disability status indicators provided by NHIS). Likewise a less conservative threshold (i.e., classifies more respondents as having a disability) can be set by including people who answered "some difficulty," "a lot of difficulty," or "cannot do at all" to at least one question.
Creating Categorical and Continuous Disability Measures
Users can also create a variable that indicates the severity of functional limitations by recording the highest level of limitation a person has on any of the domains. Someone who responded "cannot do at all" for at least one question would be labeled as "most severe," someone who did not respond "cannot do at all" for any questions but did respond "a lot of difficulty" to at least one question would be labeled as "moderate," someone who did not respond "cannot do at all" or "a lot of difficulty" to any question but did respond "some difficulty" to at least one question would be labeled as "mild," and someone who answered "no difficulty" to all questions would be labeled as "none." Users could also create a continuous measure of disability by assigning scores to response options and then summing the scores for each person across all domains to capture the disability continuum. For more information on how to construct these and additional measures of disability, please consult Creating Disability Severity Indicators.
Creating Domain Specific Disability Measures
Using the WG questions, users can also create indicators specific to one domain or a subset of domains. An example is using responses to the questions about amount of difficulty seeing and amount of difficulty hearing, users can create an indicator of deafblindness. One way to create that indicator would be to identify people who answered "cannot do at all" to either question and who answered "some difficulty," "a lot of difficulty," or "cannot do at all" to the other question. The thresholds for inclusion can be adjusted depending on the needs of the analysis. With the WG-ES, users can use similar methods using multiple questions from a single domain to create a more complete picture of functional limitations within that domain. For more information on how to construct these and additional measures of disability, please consult Creating Domain Specific Disability Indicators and Disability Identifiers Using the Washington Group Extended Set on Functioning.