Disability is difficult to define and, therefore, the prevalence of disability is difficult to measure. Nonetheless, estimates of disability prevalence are critical for reasons of policy, service provision and planning.
Traditionally, definitions have generally reflected two ways of thinking based on either the individual (or medical) model, or the social model of disability. 'Individual' definitions focus on the person and their impairment and functioning, whereas 'social' definitions emphasise the restrictions imposed upon the person by their social and physical environment.
The Equality Act (2010) defines disability as follows:
"A person has a disability if s/he has a physical or mental impairment which has a substantial and long-term adverse effect on that person's ability to carry out normal day-to-day activities." (See details here)
There is no single definition of disability that is used to measure the prevalence of disability in Scotland, as the counts and definitions are dependent upon the purposes of the measurement. Thus, a lack of comparability between definitions, together with limited data makes it difficult to gather and assess baseline information on the number of people affected by disability. The main sources of data shown within these pages of the website are the Scottish Surveys Core Questions (SSCQ) and administrative sources e.g. government departments. The latter are limited in that they are based on entitlement to particular benefits (in this case, support for people who cannot work), which not all people with a disability will claim.
The SSCQ question wording asks about physical or mental health conditions, or illnesses, lasting (or expected to last) 12 months or more. There are no population surveys in Scotland which include the term "disability" in their questions about health status and long-term conditions. Prior to 2014, the Scottish Household Survey asked whether anyone in the household had a health problem, illness or disability. The SSCQ estimate of long-term conditions is lower than that found in the Scottish Health Survey. The SSCQ is the recommended source for sub-national estimates of long-term conditions while the Scottish Health Survey is recommended for national estimates.