Measuring disability through household surveys and population censuses is challenging and there is not a gold standard approach. In censuses or surveys, disability is often captured through questions on functional difficulties (e.g. seeing, hearing), activities of daily living (e.g. bending, bathing), broad activity limitation (e.g. inability to work due to a health condition) or a general question (“do you have a disability?”).
In 2017, the United Nations Statistical Commission adopted revised guidelines for the collection of disability data in national censuses (United Nations 2017). The Commission recommends that the following four functional domains be considered essential in determining disability status in a way that can be reasonably measured using a census and that would be appropriate for international comparison: (a) Walking; (b) Seeing; (c) Hearing; (d) Cognition. It also notes that two other domains, self-care and communication, have been identified for inclusion, and if possible, upper-body functioning is another domain that should be considered for inclusion. There have been efforts to generate internationally comparable and tested questions, notably by the Washington Group (Loeb 2015; 2016).
We set out to improve disability statistics by examining existing household surveys and population censuses and analyzing data that are disaggregated by disability status.
Persons with disabilities are often invisible in national datasets
The first phase of the project consisted of reviewing national censuses and surveys and their questions related to disability for 133 low- and middle-income countries (LMICs) from 2009 to 2018. We reviewed 734 data sets and 1,297 data set-years. We found that less than a third of the data sets under review had disability-related questions. Besides, as shown on Figure 1, only 50% of countries and 15% of the datasets have functional difficulty questions that meet international standards (United Nations 2017).
Figure 1: Countries with datasets with and without functional difficulty questions
Notes: LMIC stands for low- and middle-income countries and HIC stands for high-income countries.
Source: Authors’ own calculations based on dataset review
The most commonly found disability question is the general question “Do you have a disability?” which does not produce meaningful and internationally comparable data. With such a question, people may only think of extreme disabilities and due to stigma, people may not feel comfortable answering they do. Thus, overall this review shows that persons with disabilities remain largely invisible in national household datasets in LMICs. The adoption of functional difficulty questions such as the Washington Group Short Set in national censuses and surveys and in international surveys is needed to monitor the implementation of the 2030 Agenda for Sustainable Development as well as the Convention on the Rights of Persons with Disabilities (CRPD).
Disability tends to be correlated with socioeconomic deprivations
The second part of the project consisted of analyzing the datasets that followed the United Nations Statistical Commission guidelines on functional difficulties. Using population censuses and general household surveys for 21 low- and middle-income countries, we disaggregated human development indicators across disability status to contribute to SDG target 17.18 “to increase the availability of data disaggregated by disability.” In the countries under study, disability is not rare among adults and their households with a median prevalence across countries of 10% among adults and 23% among households.
We found that for most of the indicators, there is a significant and consistent correlation between disability and socioeconomic deprivations. Among adults, disability is significantly associated with lower educational attainment, lower employment population ratios, a higher youth idle rate and a higher share of workers in the informal sector. Figure 2 illustrates the disability gap in the share of people who have ever attended school between people with and without disability measured through functional difficulties. Households with disabilities are consistently more likely to be economically insecure (food insecurity and being exposed to shocks). They also tend to have worse living conditions and fewer assets. The results confirm earlier internationally comparable analyses using the 2002 World Health Survey (World Bank WHO 2011; Mitra et al 2013).
Figure 2: Share of individuals who have ever attended school by disability (functional difficulty) status
Implications for data, research and policy
These results have implications for further research and data collection and monitoring. A measure of disability such as the Washington Group Short Set should be included as a standard correlate in studies of inequalities. As it would be inconceivable not to include age or gender as correlates, applied researchers should at least include a measure of disability based on the Washington Group Short Set or similar questions as a potential correlate of socioeconomic outcomes.
Results also suggest that disability matters when it comes to human development policy. Policy work is needed to curb the inequalities across disability status to fulfill the call to “leave no one behind” in the SDGs.
Social protection programs were found to disproportionately reach persons with disabilities in some countries and yet stark inequalities remain. Policies and programs that some LMICs have adopted after ratifying the CRPD and during the COVID-19 pandemic need to be assessed with respect to their impact on people with disabilities overall and by sex, age group, residence and other potential factors of intersectional disadvantage.
Finally, for progress to continue in research and policy analysis, internationally comparable disability questions need to become standard in censuses and general household surveys in LMICs, as well as in the monitoring systems of NGOs and governments. Results from our Inclusive Data and Statistics project overall stress the need to produce disability prevalence and disability disaggregated statistics.
These findings are now available as the World Bank Policy Research Working Paper “Invisible or Mainstream? Disability in Surveys and Censuses in Low- and Middle-Income Countries” and “Inclusive Statistics: Human Development and Disability Indicators in Low- and Middle-Income Countries”.
This project was implemented under an umbrella of the Inclusive Data and Statistics project (P170339), supported by Trust Fund for Statistical Capacity Building (TFSCB). The umbrella project aimed to contribute towards the World Bank’s commitment to disability-inclusive development, the Foreign, Commonwealth and Development Office’s (previously called Department for International Development) data disaggregation action plan, and the SDGs’ “leave no one behind” principle. Together with internal and external experts, the teams designed the framework on disability definitions across different sectors; improved survey instruments through testing and building the capacity of national statistical offices, ministries of education; and relevant professionals and supported the implementation of the Washington Group Short Set Questions on Functioning. The Inclusive Data and Statistics project wrapped up its activities in December of 2020.
Wei Chen, Justine Hervé, Sophia Pirozzi and Jaclyn Yap are co-authors of the papers.
Loeb, M. 2016. International Census/Survey Data and the Short Set of Disability Questions Developed by the Washington Group on Disability Statistics. pp. 255-304 in Altman, B. M. (ed.). 2016. International measurement of disability: Purpose, method and application, the work of the Washington Group. Social indicators research series 61. Switzerland: Springer International Publishing.
Loeb, M. 2015. Disaggregation by disability: a way forward. Accessed Nov. 1st 2020 at: https://www.cbm.org/news/news/news-2015/disaggregation-by-disability-a-way-forward/
Mitra, S., Posarac, A. and Vick, B. (2013). Disability and Poverty in Developing Countries: a Multidimensional Study. World Development Vol. 41; pp.1-18.
United Nations (2017) Principles and Recommendations for Population and Housing Censuses. United Nations Department of Social and Economic Affairs. ST/ESA/STAT/SER.M/67/Rev.3. Accessed on Dec. 22nd 2020: https://unstats.un.org/unsd/demographic-social/Standards-and-Methods/files/Principles_and_Recommendations/Population-and-Housing-Censuses/Series_M67rev3-E.pdf
WHO-World Bank (2011) World Report on Disability. World Health Organization: Geneva.