|
The Disabled Workforce
Key Definitions of Statistical Terms
Prevalence refers to the number of people with the defined characteristic.
Incidence refers to the number of new cases per year.
Legal blindness is a level of visual impairment that has been defined by law to determine eligibility for benefits. It refers to central visual acuity of 20/200 or less in the better eye with the best possible correction, as measured on a Snellen vision chart, or a visual field of 20 degrees or less.
Functional limitation refers to the consequence of different levels of visual ability for the performance of common activities. The activity usually measured is the function of reading. Functional limitation in seeing print is measured by self- or proxy-survey report for two levels:
- Severe functional limitation in seeing refers to people who said they "are unable" to see words and letters in ordinary print, even with their eyeglasses on.
Americans with Disabilities 1991 - 1992: Data from the Survey of Income and Program Participation
Basic statistics, US disabilities
Digest of Data on Persons with Disabilities 1992
|
