self-reporting. Finally, the general disability question tends to lead to underestimates of disability prevalence (Mont, 2007) as they capture severe impairments and tend to miss disabilities associated with old age as older people may not think of themselves as disabled but simply as older persons. For these reasons, it is not considered good practice to use the general disability question, let alone for the purpose of producing internationally-comparable statistics on disability.

Yet, likely due to its conciseness and a lack of awareness on its drawbacks, this question can still be found in some surveys and censuses and this paper examines in the next section to what extent this has continued to be the case in the past decade.

# **Other disability-related questions**

There are many other types of disability questions beside functional difficulties, ADL, broad activity limitations, and general disability questions. Some surveys such as the Model Disability Survey have questions on barriers people may face in their environment, whether physical, social, or attitudinal. These are particularly useful in understanding the drivers of difficulties or deprivations people may experience.

In some countries, surveys or censuses ask respondents if they are part of an official registry of people with disabilities which would give them access to services or benefits. More often, surveys have questions on impairments and on specific health conditions.

Health conditions may be temporary or chronic, physical, or mental, life threatening or not, infectious or non-communicable. Not everyone has access to health services, which is necessary to have a diagnosis associated with doctor/clinic visit or hospitalization. Such questions, in fact, identify those with a diagnosis as among those with access to health care, which may be a small minority in the global south. In order to capture health conditions among those who may not have received a diagnosis, some questionnaires attempt to find out if respondents have experienced certain symptoms and to figure out if the person has specific health conditions. This would be the case, for instance, with depression for which a questionnaire may ask about a person’s thoughts about death or difficulty sleeping at night. However, this method may require a lot of questions and may not be feasible for all health conditions. Several of the questionnaires noted earlier such as the WG Enhanced and Extended Sets and the Model Disability Survey questionnaire do have questions that try to get at the symptoms of some conditions, particularly depression.

Finally, some questionnaires such as the Model Disability Survey questionnaire and WHO - DAS (WHO 2012) blend several of the disability question types discussed above. WHO-DAS 2.0 has a mix of functional, ADL and broad activity limitations. The Model Disability Survey has questions on functional difficulties, ADL, broad activity limitations, health conditions and environmental factors. This paper reviews the questionnaires in surveys and censuses in low- and middle-income countries and the extent to which they include any disability-related questions and what type of disability question.

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