475. 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 on-going 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)⁶. Census data can be utilized for planning programmes and services (prevention and rehabilitation), monitoring disability trends in the country, evaluation of national programmes and services concerning the equalization of opportunities, and for international comparison of the disability prevalence in countries. Census data on disability can also be used by countries to produce and disseminate the statistics required by the Convention on the Rights of Persons with Disabilities.⁷

476. According to the CES Recommendations, disability status characterises the population into those with or without a disability. Persons with disabilities were defined by the CESR (paragraph 733) as those persons: “….who are at greater risk than the general population for experiencing restrictions in performing specific tasks or participating in role activities. This group would include persons who experience limitations in basic activity functioning, such as walking or hearing, even if such limitations were 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 activities, such as working or going to church, because the necessary adaptations have been made at the person or environmental levels. These persons would 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 jeopardise their current levels of participation”.

477. The CES Recommended that at least the first four of the six domains recognised by the Washington Group on Disability Statistics (WG)⁸ as being essential in determining disability should be identified. These are:

(a) walking

(b) seeing

(c) hearing

(d) cognition

478. The CESR also suggested that if countries wished they could consider self-care and communication as two additional domains. The full set of WG questions – including the six domains – is often referred to as the Washington Group Short Set of questions on Disability (WG Short Set).

479. It is generally the case, however, that the full set of WG questions is not practicable in a census context where questionnaires are often designed for self-completion and where there is intensive competition for space on the questionnaire.

480. Information on the collection of data on disability in the 2020 census round, based on the UNECE survey, is presented in Table 89. Disability was included in the census by 21 countries out of 47 (44%), including 71% of countries with field enumeration census, 53% of those with a combined census and none of those with a register-based census. In Canada the census does not collect information on disability, but includes questions to determine the sample frame for a post-censal survey "Canadian Survey on Disability". Similarly, in Switzerland the Swiss Health Survey is carried out every 5 years (2012, 2017, 2022) as part of the Swiss population census. Of the countries that collected data on disability, the large majority used full enumeration (18 countries) and only 3 used sample data.

481. Over half of the countries that collected information on disability used the WG Short Set (13 countries), as recommended, in almost all cases with no changes. About two thirds of the countries that used the WG Short Set asked the questions on all six domains, and one third asked only the questions on the four domains recommended by the CES.

482. Half of the countries collected information on disability for all persons in the household, and the other half only for persons over a specific age, which was in general five years, or two years for vision, hearing and mobility. Only one country (Poland) used filter questions.

483. The UNECE survey also asked countries whether they used any child-specific disability measurement tool, such as the Washington Group/UNICEF Child Functioning Modules (CFM) (for children aged 2-4 years and for children aged 5-17 years). Only two countries reported using such tools: Georgia used both CFM 2-4 and CFM 5-17, and North Macedonia used only CFM 5-17.

484. Finally, countries were asked whether they experienced any difficulties collecting disability data on the census or determining disability status from other sources: ten countries reported some difficulties, including poor understanding of questions (5 countries), difficulty interpreting responses received (5 countries), low response or coverage (4 countries), or the subjective character of the questions (3 countries).

	Total (out of 48 countries)	Type of census
		Field enumeration (17 countries)	Combined (17 countries)	Register-based (14 countries)
Information collected	21	12	9	0
Main data source:
full enumeration	18	11	7	0
sample data	3	1	2	0
registers/admin.rec.	0	0	0	0
Was the Washington Group Short Set on Functioning (WG-SS) used?
Yes, all six questions, with no changes	8	3	5	0
Yes, a subset (less than six), with no changes	5	4	1	0
Yes, we made changes to some or all the WG-SS questions	1	0	1	0
We did not use any of the WG-SS questions	2	0	2	0
No	4	4	0	0
Which of the WG-SS questions were used?
Vision	15	9	6	0
Hearing	14	8	6	0
Mobility	15	9	6	0
Cognition (remembering)	15	9	6	0
Self-care	11	5	6	0
Communication	9	4	5	0
Does the information on disability relate to all persons in the household?
Yes	11	8	3	0
No, information only related to persons over a specific age	9	4	5	0
No, a filter or screening question was used	1	0	1	0
Information not collected	27	5	8	14