The UN Convention on the Rights of Persons with Disabilities (CRPD) protects all persons with disabilities. They are defined in Article 1 as including “… those who have long-term physical, mental, intellectual or sensory impairments which in interaction with various barriers may hinder their full and effective participation in society on an equal basis with others.”

This broad definition adopts what is known as the social model of disability. It recognises that disability is an evolving concept, and that we are often prevented from exercising all of our human rights and fundamental freedoms by barriers of attitude and environment which have been placed in our way. In other words, the Convention seeks to alter social attitudes by ensuring that governments, individuals and organisations recognise that we have the same human rights and fundamental freedoms as all other persons.

The WHO defines disability as an umbrella term for impairments, activity limitations, and participation restrictions that result from the interaction between a person's health condition and environmental factors.

It is worth noting that the prevalence of disability can vary widely across different populations and regions, and the WHO's estimates are based on available data and statistical modeling.

ADAAA defines a person with a disability as a anyone with a physical or mental impairment that substantially limits one or more major life activities; has a record of such an impairment; or is regarded as having such an impairment. 

For the purposes of this analysis, a person is considered to have a disability if they have a self-reported long-standing illness, condition or impairment, which causes difficulty with day-to-day activities.