Statistics for the number of deaf people are a huge problem. Most census counts tend to ignore deaf people as a separate category. When deaf people are recognized at all, they are usually lumped in with all other disabled/handicapped people or, if the census is conscientious about differentiating among disabilities, will lump all individuals with "hearing loss" together.
"Hearing loss" is another big problem; it brings up questions about the definition of "deaf": at what point does a person cross over from "hearing" to "hard of hearing", from "hard of hearing" to "deaf"? Also, do you count only people who are pre-lingually deaf, or do you count late-deafened people too? Do you include people who become deaf from old age? Depending on where the dividing line is set, the count can vary wildly.
Another difficulty is in the way that statistics may be given. They may be given as:
- a numerical quantity ("There are about 5,000 deaf people in Lower Slobbovia");
- a prevalence rate ("There are .7 deaf people per 1000 in Lower Slobbovia" [or "7 per 10,000", "70 per 100,000", etc.]); or
- a percentage (".07% of the Lower Slobbovian population is deaf").
Thus, if you wish to compare the statistics for two different countries, or compare two different statistics for the same country, you may have to do some mathematical conversion to get directly comparable numbers. For prevalence and percentage, you also need to find the total national population in order to compute the number of deaf people.
Cutoff ages for children may also vary: ages 5-19, ages 3-21, ages 6-18, etc. In general, figures for very young deaf children are not available due to the problems and uncertainties of identifying deafness in that age group.
There is a good discussion of the difficulties of counting deaf people, and of interpreting the resulting figures, in the article by Jerome D. Schein, "Deaf population", in the Gallaudet encyclopedia of deaf people and deafness (New York: McGraw-Hill, 1987), volume 1, pages 251-256. A perusal of Holt, Judith A., and Hotto, Sue A., Demographic aspects of hearing impairment: questions and answers (Washington, D.C.: Gallaudet University, Office of Assessment and Demographic Studies, 1994; available online at http://research.gallaudet.edu/Demographics/factsheet.php/), will also shed much light on the problems of defining and counting what is meant by a "deaf person". Although those articles may seem outdated, the problem of evaluating the demographics of being deaf is perennial, and no decisive solution has yet been found.
One recent approach, taken by NTID researchers in their 2012 report, Number of persons who are deaf or hard of hearing: Rochester, NY, averages a nationwide prevalence of deafness at approximately 3.5%, based on the American Community Survey from the Census. They also address the problem of age distribution and definitional difficulties in such an undertaking.
When looking at a figure offered for the number of deaf people, ask yourself these questions:
- How was "deaf" defined for this purpose?
- How are the figures expressed: numerical quantity, percentage, or prevalence?
- Who is doing the counting?
- Does this source have any reason to want to distort the numbers one way or the other? (For example, an organization of the deaf might want to skew the numbers to the high side, to make its population appear more important. On the other hand, a national government might want to lower the numbers to make its population's level of health appear better.)
- How reliable and believable is this source?
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Reference and Instruction Librarian
Updated: September, 2012