Measuring disability through household or population surveys is difficult and there is no gold standard approach. Censuses and surveys often capture disability through questions about functional difficulties (e.g. vision, hearing), activities of daily living (e.g. bending, bathing), broad activity limitations (e.g. inability to work due to a health condition), or through a general question (“Do you have a disability?”).
In 2017, the United Nations Statistical Commission adopted revised guidelines for collecting disability data in censuses (United Nations 2017). The Commission recommends that four areas of function be considered essential to determine disability status in a way that can be reasonably measured using the census and is suitable for international comparison: (a) walking, (b) vision, (c) hearing, and (d) cognition. It also identifies two other areas for surveying: self-care and communication, and notes that upper body function is another area that should be considered for surveying, if possible. Efforts to develop internationally comparable and tested questions are underway, notably by the Washington Group (Loeb 2015, 2016).
We set out to improve disability statistics by examining existing household and census data and analysing the data disaggregated by disability status.
People with disabilities are often invisible in national data
The first phase of the project considered censuses and surveys and disability-related questions conducted in 133 low- and middle-income countries (LMICs) between 2009 and 2018. After considering 734 data sets and 1,297 data set-years, we found that less than one-third of the data sets considered included disability-related questions. Furthermore, as shown in Figure 1, only 50% of countries and 15% of data sets included questions about functional difficulties that met international standards (United Nations 2017).
Figure 1: Countries with datasets with and without questions about functional difficulties
Note: LMIC stands for low- and middle-income countries, and HIC stands for high-income countries.
Source: Authors’ own calculations based on review of the dataset.
The most common question on disability is the general question “Do you have a disability?”, but this does not produce meaningful internationally comparable data. With such a question, people may only think of severe disabilities and may feel reluctant to answer that they have a disability due to stigma. Overall, this review therefore shows that people with disabilities remain largely invisible in national household datasets in low- and middle-income countries. Adopting questions on functional difficulties, such as the Washington Group Short Set, in censuses and surveys, as well as international surveys, is necessary to monitor the implementation of the 2030 Agenda for Sustainable Development and the Convention on the Rights of Persons with Disabilities (CRPD).
Disability tends to correlate with socio-economic deprivation
The second part of the project was the analysis of a dataset following the UN Statistical Commission guidelines on disability. Population and general household surveys from 21 low- and middle-income countries were used to disaggregate human development indicators by disability status, contributing to SDG target 17.18 “Increase the availability of disability-disaggregated data”. Disabilities are not uncommon among adults and their households in the countries studied, with national average prevalence rates of 10% for adults and 23% for households.
We found a significant and consistent correlation between disability and socio-economic deprivation across most of the indicators. For adults, disability is significantly associated with lower educational attainment, lower employment-population ratios, higher youth inactivity and higher proportion of informal sector workers. Figure 2 shows the disparity in the proportion of people with and without disabilities who have ever attended school, measured by functional difficulties. Households with disabilities are consistently more likely to be economically unstable (more food insecure and exposed to shocks). They are also more likely to have poorer living conditions and fewer assets. This finding supports previous internationally comparable analyses using the 2002 World Health Survey (World Bank WHO 2011; Mitra et al. 2013).
Figure 2: Percentage of people who have attended school by disability (functional difficulty) status
Data, research and policy implications
These results have implications for further research and data collection and monitoring. Measures of disability such as the Washington Group Short Set should be included as standard correlates in studies of inequality. Because it is unthinkable not to include age and sex as correlates, applied researchers should at least include measures of disability based on the Washington Group Short Set or similar questions as potential correlates of socioeconomic outcomes.
The results also suggest that disability matters with regard to human development policies: policy action to reduce inequalities based on disability status is needed to meet the SDGs’ requirement to “leave no one behind”.
Social protection programmes have been found to disproportionately reach people with disabilities in some countries, but significant inequalities remain. Policies and programmes adopted by some low- and middle-income countries since ratifying the CRPD and during the COVID-19 pandemic need to be assessed for their impact on people with disabilities overall, by gender, age group, location and other potential intersecting sources of disadvantage.
Finally, to continue to advance research and policy analysis, internationally comparable questions on disability need to become standard in censuses and general household surveys in low- and middle-income countries, as well as in NGO and government monitoring systems. Overall, the results of our Comprehensive Data and Statistics Project highlight the need to produce disability prevalence and disability disaggregation statistics.
These findings have now been published as World Bank Policy Research Working Papers: “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 as part of the Inclusive Data and Statistics Project (P170339) supported by the Trust Fund for Statistical Capacity Building (TFSCB). The inclusive project aimed to contribute to the World Bank’s disability inclusive development efforts, the Foreign, Commonwealth and Development Office (formerly Department for International Development) Data Disaggregation Action Plan, and the “Leave No One Behind” principle of the SDGs. With internal and external experts, the team designed a framework on disability definition across sectors, improved the survey instrument by testing and building capacity of national statistical offices, ministries of education, and relevant experts, and supported the implementation of a short-term question set on the capabilities of the Washington Group. The Inclusive Data and Statistics Project concluded its activities in December 2020.
Wei Chen, Justine Hervé, Sophia Pirozzi and Jaclyn Yap are co-authors of the paper.
References
Loeb, M. 2016. International Census/Survey Data and a Short Question Set on Disability Developed by the Washington Disability Statistics Group. pp. 255-304. Altman, BM (ed.) 2016. International Disability Measurement: Purposes, Methods, Applications, 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 November 1, 2020: 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 multi-dimensional study. World Development 41, pp.1-18.
United Nations (2017) Principles and Recommendations for the Population and Housing Censuses. United Nations Department of Social and Economic Affairs. ST/ESA/STAT/SER.M/67/Rev.3. Accessed 22 December 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.