The U.S. Census Bureau, using research and survey work done by them and by the Social Security Administration, developed the definition of work disability for use in the CPS and began using it in the March Supplement survey in 1981.  As early as 1983, the Census Bureau began publishing data based on this definition.  This first publication, Labor Force Status and Other Characteristics of Persons With a Work Disability:  1982 was updated in 1989.

Opponents of CPS data sometimes quote a government definition of disability not measured in the CPS (“persons with a physical or mental impairment which substantially limits one or more of the major life activities”).  This definition, however, is not the appropriate definition of disability to use in tort cases involving lost earnings.  The definition quoted above is a much broader one that, though consistent with the Americans with Disabilities Act, includes people who do not have limitations in the kind or amount of work they can perform.  For forensic purposes, when assessing loss of lifetime earnings, the most important and relevant focus is on persons who have a work disability, the definition used in the CPS.  This is the exact issue addressed by Mr. John McNeil, formerly with the Census Bureau, in an affidavit.