(WGSS), an enhanced short set of 12 questions (WGSS-enhanced), an extended list of more than 30 questions (WGES), and finally a functioning module for children developed in collaboration with UNICEF (Altman 2016, Adans et al 2018). The recommended short set includes six questions on limitations in the domains of seeing, hearing, walking or climbing steps, concentrating, communicating, and self-care (specifically, showering or dressing). The United Nations encourages governments to include (at least) the short set of questions recommended by the Washington Group in censuses and surveys. This option of using the short set of questions to measure disability does not capture all areas of functioning and would not satisfy all data needs but does provide a way to use population censuses and mainstream household surveys to monitor the SDGs and the CRPD.<sup>1</sup> In light of disability data needs to monitor the 2030 Agenda and the CRPD and recent progress in developing and testing internationally-comparable disability questions, the goal of this paper is to review the extent to which household surveys and population censuses include disability questions in low- and middle-income countries from 2009 to 2018. Section 2 provides background on measuring disability through household surveys and censuses. Section 3 reviews different types of questions on disability, and section 4 describes the data sets under review. Section 5 presents the results and section 6 provides the discussion and conclusion.

# **2. Background**

Measuring disability through household surveys and population censuses is a very complicated task and there is not a gold standard approach. How disability is measured depends on the objective of the measurement exercise. The goal might be to document disability prevalence and incidence, assess inequalities associated with disabilities, or evaluate service needs as well as policies and laws.

More fundamentally, measurement also reflects how disability is understood and defined, whether implicitly or explicitly. Because disability can be defined in a variety of ways, it can also be measured in many ways. Different conceptual models have been developed to define disability (Davis 2017; Goodley 2016). For instance, the medical model treats disability as a problem of the individual requiring medical treatment and rehabilitation. An individual with an impairment is considered disabled irrespective of whether it limits functioning and activities. On the other hand, the social model considers disability as socially created. Disability is not about the individual, but about the social environment in which the person lives. For instance, a person with a physical impairment may be unable to work because workplaces lack ramps and elevators and, thus, are inaccessible. Since the 2000s, disability has often been defined through interactional models as a biopsychosocial phenomenon, one that results from an individual with a health condition interacting with environmental factors. This understanding is for instance consistent with the commonly used International Classification of Functioning, Disability, and Health (ICF) (WHO 2001). In the ICF, functioning refers to body functions and structures, activities and participation, while disability is an umbrella term for impairment (e.g. blindness),

> 1 The data collection options above could be blended. There could be a short questionnaire (e.g. WGSS or the WGSS-enhanced) as part of a core questionnaire and then special modules added from time to time to capture for instance environmental barriers and other determinants of inequalities. For instance, this is the approach used by ILO (WG-ILO 2020) in its recommendations for Labor Force Surveys.

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