Chapter 22 Disability
22.1 Rationale for inclusion of disability in censuses 
1367.
1367. A census can provide valuable information on disability in a country. For countries that do not have regular special population-based disability surveys or disability modules in ongoing surveys, the census can be the only source of information on the frequency and distribution of disability in the population at national, regional and local levels. Countries that have a registration system providing regular data on persons with the most severe types of impairments may use the census to complement these data with information related to the broader concept of disability based on the International Classification of Functioning, Disability and Health (ICF) described below. Census data on disability can be used for planning programmes and services related to prevention, mitigation and rehabilitation; for monitoring disability trends in the country; for evaluation of national programmes and services concerning the equalization of opportunities, and for international comparison of the prevalence of disabilities in countries, including in the context of internationally-agreed monitoring frameworks such as the Sustainable Development Goals (SDGs) or their successors. Census data on disability can also be used by countries to produce and disseminate the statistics required in order to comply with the Convention on the Rights of Persons with Disabilities.133
1368.
1368. Three major classes of purpose for measuring disability in a census are:
(a) To provide services, including the development of programmes and policies for service provision and the evaluation of these programmes and services. The provision of services at the population level includes, but is not limited to, addressing needs for housing, transportation, assistive technology, vocational or educational rehabilitation, and long-term care.
(b) To monitor the level of functioning in the population. Monitoring levels of functioning includes estimating rates and analysing trends. The level of functioning in the population is considered a primary health and social indicator, which characterizes the status of the population in a society.
(c) To assess equalization of opportunities. The assessment of equalization of opportunity involves monitoring and evaluating outcomes of anti-discrimination laws and policies, and service and rehabilitation programmes designed to improve and equalize the participation of persons with impairments in all aspects of life.
1369.
1369. The intent of these purposes for measurement is consistent with that of the World Programme of Action concerning Disabled Persons (WPA),134 which provides a valuable guide for conceptualizing the uses of data on disability. The WPA outlines three major goals for policy formulation and programme planning, internationally: equalization of opportunities, rehabilitation and prevention. The common goal is to promote the participation of persons with disabilities in all aspects of life by preventing the onset and consequences of impairments, promoting optimal levels of functioning, and equalizing opportunities for participation.
1370.
1370. The assessment of equalization of opportunity is the purpose that can be best achieved in a census. It is this purpose that is considered when determining “disability status” (see paragraph 1377).
1371.
1371. The definition outlined in paragraph 1377 requires that disability be defined in terms of limitations in basic activity functioning that would place a person at greater risk than the general population of restricted performance or participation in the organized activities (such as educational attendance or work participation).
1372.
1372. While assessment of equalization of opportunities might seem to require measurement of both activities and participation, such an approach does not help to identify changes in the level of participation in the population in response to changes in opportunities. It only reflects the circumstances of those who, because of unfriendly environments or lack of assistive devices, are experiencing restrictions in participation. Approaching the assessment of equalization of opportunity by recognizing the link between a basic level of activity and subsequent participation can reduce some of the methodological challenges.
1373.
1373. Disentangling the conceptual dimensions of basic activity limitations that result from impairment, from the more complex activities associated with participation provides the opportunity to determine the intervening mechanisms that facilitate or interfere with performance of tasks and organized activity. At the analysis stage, persons who are identified with or without disabilities on the basis of their ability to perform basic activities can be compared in relation to their participation in organized activities (such as school and work). This comparison can assess the equalization of opportunities. The separation between activities and performance differentiates approaches for the purpose of monitoring functioning in the population and for the purpose of assessing equalization of opportunity. When assessing opportunity equalization, the connection between the conceptual elements is made during analysis, whereas for monitoring functioning the connection is done during data collection.
1374.
1374. Within the framework of the ICF Model and its four major dimensions (body structure and function, activity, participation and environment), an activity-oriented set of questions, located at the simplest and most basic level, should be used to capture the basic activity elements required for a good measure of the risk of participation restrictions.
1375.
1375. The adoption of an activity-oriented approach is also used in the European Health Status Module developed by Eurostat within the European Statistical System. Although it has been designed for more extended data collection activities such as the European Health Interview Survey, it still can be used to identify questions to measure activity limitations in a census. This module also includes the Minimum European Health Module (MEHM),135 a set of three general questions characterizing three different concepts of health (self-perceived health, chronic morbidity and activity limitations).
1376.
1376. Given the complexity of disability definition and measurement, and, in certain cultures, the sensitivity attached to identifying a person as having a disability, it is recommended that several functional activity domains be defined whereby people can respond to questions about their difficulty performing those activities rather than directly enquiring whether they have any disability.
22.2 Disability status (non-core topic)
1377.
1377. Disability status characterizes the population as those with and without a disability. Persons with disabilities are defined as those persons who are at greater risk than the general population for experiencing restrictions in performing specific tasks or participating in activities. This group includes persons who experience limitations in basic activity functioning, such as walking or hearing, even if such limitations are ameliorated by the use of assistive devices, a supportive environment or plentiful resources. Such persons may not necessarily experience limitations in tasks, such as bathing or dressing, or participation in activities, such as working, shopping or attending a place of worship, because the necessary adaptations have been made at the person or environmental levels. These persons should still, however, be considered to be at greater risk for restrictions in activities and/or participation than the general population because of the presence of limitations in basic activity functioning and because the absence of the current level of accommodation would preclude their current levels of participation.
1378.
1378. A comprehensive measure to determine disability should include the six domains of functioning identified by the Washington Group on Disability Statistics:136
(a) walking
(b) seeing
(c) hearing
(d) cognition
(e) self-care
(f) communication.
1379.
1379. The first four domains are essential for determining disability status, while the fifth and sixth domains permit a more comprehensive measure for determining disability status.
22.3 Disability framework and terminology
22.3.1 International Classification of Functioning, Disability and Health (ICF)
1380.
1380. The ICF is a classification system issued by the World Health Organization (WHO), offering a conceptual framework with concepts, definitions and terminology, and classifications of contextual components associated with disability, including both participation and environmental factors.
1381.
1381. The ICF distinguishes multiple dimensions that can be used to monitor the situation of individuals with a disability. The system is divided into two parts, each with two components;
(1.0)Functioning and disability, which include the components:
(1.1)Body functions and body structures (impairments)
(1.2)Activities (limitations) and participation (restrictions)
(2.0)Contextual factors which include the components:
(2.1)Environmental factors
(2.2)Personal factors
1382.
1382. The ICF provides classification schemes for all these elements except for personal factors.
22.3.2 Census questions
1383.
1383. A census format offers only limited space and time for questions for one topic such as disability. Since the ICF offers several dimensions for use to develop a census measure, it is best to focus on a few of those dimensions, leaving the remaining dimensions for use in more extensive household surveys. Short sets of disability questions, which can be included in censuses and extended sets to be recommended for inclusion in population-based surveys have been developed and tested. The aim of the recommended sets is to improve comparability of disability data across countries. An example of short set of disability questions that can be used in population censuses is the Short Set on Functioning developed by the Washington Group on Disability Statistics (WG-SS).137 Extended sets of disability questions designed for population-based surveys are not suitable for use in censuses because of their length of complexity, time constraints, and special training required for the enumerators, impossible to provide in a population census.
1384.
1384. Due to the sensitivity of the topic, it is recommended that special attention should be paid in designing census questions to measure disability. The wording and the construct of questions greatly affect the precision in identifying the persons with disabilities. The result can also be significantly influenced by the data collection method used (interview or self-compilation). Ideally, each domain should be asked through a separate question.138 The language used should be clear, unambiguous and simple. Negative terms should always be avoided.
1385.
1385. The disability questions should be asked about each single household member aged five years and above and general questions on the presence of persons with disabilities in the household should be avoided. Information on census questions on disability for children is provided in Box 8.
1386.
1386. If necessary, a proxy respondent can be used to report for the family member who cannot respond for himself or herself. Scaled response categories can also improve the reporting of disability. The census questions on disability endorsed by the Washington Group include four response categories:
(a) No difficulty;
(b) Yes – some difficulty;
(c) Yes – a lot of difficulty; and
(d) Cannot do [function] at all
1387.
1387. Disability prevalence is determined based on any response that is “a lot of difficulty” or “cannot do at all” for any of the domains.
1388.
1388. The European Health Status Module (see paragraph 1375) includes a set of standard questions for various domains and can be used as source to develop census questions in three of the four core domains (seeing, hearing and walking). There is also a set of questions for use on national censuses for gathering information on the four essential domains.139 The questions have been designed to provide comparable data cross-nationally for populations living in a great variety of cultures with varying economic resources. The objective is to identify persons with similar types and levels of limitations in functional activities regardless of nationality or culture. It is not the purpose of these questions to identify every person with a disability within every community. The questions may not meet all the needs for disability statistics, nor will it replicate a population evaluated across a wider range of domains that would be possible in other forms of data collection or in administrative data.
1389.
1389. The information that results from measuring disability status is expected to:
(a) represent the majority, but not all persons with limitation in basic activity functioning in any one country;
(b) represent the most commonly occurring basic activity limitations within any country; and
(c) capture persons with similar problems across countries.
1390.
1390. The questions identify the population with functional limitations that have the potential to limit independent participation in society. The intended use of these data would be to compare levels of participation in employment, education, or family life for those with disability versus those without to see if persons with disability have achieved social inclusion. In addition the data could be used to monitor prevalence trends for persons with limitations in the particular basic activity domains. It would not represent the total population with limitations, nor would it necessarily represent the “true” population with disability, which would require measuring limitation in all domains.
Box 8
Census questions on disability for children
Census questions on disability for children
To measure disability among children accurately, questions need to cover a comprehensive range of functional domains and administration of such questions needs to be done to the child’s mother or primary caregiver. A specific set of questions to identify children with disabilities, called Child Functioning Module (CFM), has been developed through a collaboration between the Washington Group on Disability Statistics and UNICEF.140 In addition to collecting data on domains related to physical, sensory and cognitive functioning, the CFM includes questions on difficulties in psychosocial functioning. The questions need to be answered by the mothers or primary caregivers, as these are the best informants when obtaining information on children.
Because of the space restrictions inherent in the census format, and given that the child’s mother or primary caregiver is unlikely to be the respondent to the census questionnaires, the CFM is not best suited for use in censuses.
Countries may consider using the Washington Group Short Set on Functioning (WG-SS). However, the use of the WG-SS has limitations when used for children. The WG-SS, like any other set of questions, should never be used to capture disability in children less than five years of age. For children aged 5 to 17 years, the use of the WG-SS will significantly underestimate the size of the population of children with disabilities. The reason is twofold. Firstly, it is because the WG-SS does not capture information on key domains of child functioning, including learning, interacting with peers, coping with change, focusing attention and management of emotions. Secondly, when data are collected from respondents other than the child’s mother or primary caregiver as it is the case in a census, the likelihood of underestimating the size of the population of children with disabilities increases significantly. For these reasons, if the WG-SS is used for children aged 5 to 17 years, it is essential to emphasize in the presentation of the results that the size of the population of children with disabilities is underestimated.
22.4 Use of the census to screen for disability and follow-up with other surveys
1391.
1391. Countries that are planning specialized surveys on disability may want to use the census to develop a sampling frame for these surveys and include a screening instrument to identify persons who will be interviewed subsequently. The definitions and the instruments used for this purpose are very different from the ones used to assess equal opportunities. The main purpose of a screening is to be the most inclusive as possible in order to identify the largest group of people who could be further studied. The screening question should be designed so that false negatives (that is, persons who have disabilities but are not identified in the census as having disabilities) are minimized, while false positives (persons who are identified with disabilities in the census but in reality they do not have disabilities, as assessed in the largest instrument used in the follow-up survey) should be less of a concern.
1392.
1392. Within the framework of the ICF, the census screening may include all of the three main dimensions of body structure and function, activity and participation. This will allow for keeping a broad approach to the follow-up survey where the different aspects of disability can be better studied.
1393.
1394.
1394. Before embarking on using the census to develop a frame for a follow-up survey, it is important that the legal implications of using personal census data for this purpose are fully considered. Respondents should be informed beforehand that the data may be used for follow-up studies, and national authorities responsible for ensuring the privacy rights of the population may need to be consulted in order to obtain their approval.
1395.
1395. Further detail on disability can be found in the United Nations Principles and Recommendations – Revision 4, Part five, Chapter IV (Definitions and specifications of topics), section D (Demographic and social characteristics), sub-section 9 (Disability status), paragraphs 5.214-5.236.