Nonforensic researchers have used data from various studies to measure the effect of disability on employment.  Even those studies using definitions that are not specific to work disability have found that disability negatively impacts employment and earnings.  Kaye (1998) summarized findings from various surveys, including the CPS, SIPP, NHIS, and Harris Survey, and noted the existence of an earnings and employment discrepancy between people with and without disability. 

Trupin and Yelin (1999) used data from the California Work and Health Survey, which defined disability as existing in those with physical functional limitation.  They found that people with disability had a lower labor force participation rate, were more likely unemployed, and more likely to be employed in part-time or temporary jobs.  

DeLeire (2000) used the SIPP and found that people with a disability work less and earn less than people with no disability.  Also, in the few years following passage of the ADA, men with disability were less likely to be employed relative to men with no disability than they had been in the few years prior to passage of the ADA.  In the few years prior to the ADA, men with disability had employment rates that were 63% as high as the rate for men without disability.  In the few years after the ADA, this rate dropped to 53% (DeLeire, 2000).  McNeil (2001) used SIPP data collected in 1997 and again found reduced employment and earnings for persons with both severe and nonsevere disability.