Figure 7. DISABILITY CATEGORIES EMPLOYED IN THE LATEST THREE CENSUSES OF TUNISIA AND ZAMBIA

Sources: Republic of Zambia, Census of Population and Housing 1969, Final Report Volume I-Total Zambia (Lusaka, Central Statistical Office, 1973, pp. 11-14, Table 4 and p. 36, Table 18 and Tunisia, Institut national de la statistique, Recensement general de la population et des logements, 8 Mai 1975, Volume III, Caracteristiques demographiques, tableaux et analyses des resultats du sondage au 1/10eme75 (Tunis, Author, 1975) and Recensement general de la population et de l'habitat, 30 Mars 1984, Volume IV, Caracteristiques demographiques (Tunis, Author, 1984).

The most extreme change in approach is probably the dropping of the sick category by Zambia between its second and third census. If one only examines the total disability rate for Zambia over time, one would conclude that there has been a steady decline in the prevalence of disability between 1969 and 1990. While this may have been true between 1969 and 1980, as documented by figure 8, the observed decline between 1980 and 1990 was totally caused by the elimination of the category for sick in 1990. In 1969 and 1980, those counted as sick accounted for 50.8 per cent and 37.8 per cent of the reported population with disabilities. Even if one assumes some that: (a) the prevalence rates for sickness dropped between 1980 and 1990 in a similar manner to the drop between 1969 and 1980 and (b) some persons who may have been reported as sick were reported in other categories in 1990, the elimination of that reporting category has an effect on how the data are interpreted. If the trend between 1980 and 1990 is examined employing the 1990 disability reporting structure, the prevalence rate per 100,000 did not decline from 1,615 to 936 but actually increased from 610 to 936 per 100,000. Here is a case in which the categories reported as disabilities may actually influence the resulting trend.

Sources: Republic of Zambia, Census of Population and Housing 1969, Final Report Volume I-Total Zambia (Lusaka, Central Statistical Office, 1973, pp. 11-14, Table 4 and p. 36, Table 18.

The focus here is not on whether Zambia should or should not have included the "sick" category as a reported disability category. The important point is that any change in this important decision has important ramifications. Zambia simply dropped the category, which made it possible to examine the changes in the other categories between 1980 and 1990 (assuming the other wording changes did not influence the resulting trend).

b) The changing disabled population

In the case of Canada, a Disability approach has been employed in three recent surveys over an eight year period. For example, the "Canadian Health and Disability Survey of 1983-84" counted children as disabled if they were reported as (a) using an aid or prostheses, (b) having a long-term health condition limiting activities, (c) attending a special school or class because of a condition, (d) having a specified impairment, (e) having vision or hearing trouble or (f) having a long-term health condition expected to last more than six months. The 1986 and 1991 Health and Activity Limitation Surveys employed similar definitions for children with disabilities.

From the three points in time for Canada, the data would suggest that the prevalence of disability is increasing. Confidence in that conclusion is increased by the consistency of the increase for both men and women, as shown in figure 9. Indeed, disability appears to be more prevalent in women, which, along with age, is strongly associated with the observed increase. In developed countries, disability rates increase with age, life expectancies are increasing and life expectancies for women are greater than for men. If disability rates increase with age and life expectancies are increasing, given no other change, the disability prevalence rate will increase over time. However, in Canada, the prevalence of disability is increasing within the age groups, as demonstrated by figure 10. Indeed, the rate is increasing among persons 65 years of age and over and for both men and women, as documented in figure 11. As more women enter the 65 years and over age group where women are more numerous than men and where female disability rates are higher than for males, overall disability prevalence will rise.

Sources: Statistics Canada, Health Division and Department of the Secretary of State, Social trends analysis directorate, 1986; Report of the Canadian health and disability survey, 1983-84 (Ottawa, Author, 1986).

Sources: Statistics Canada, Health Division and Department of the Secretary of State, Social trends analysis directorate, 1986; Report of the Canadian health and disability survey, 1983-84 (Ottawa, Author, 1986).

Sources: Statistics Canada, Health Division and Department of the Secretary of State, Social trends analysis directorate, 1986; Report of the Canadian health and disability survey, 1983-84 (Ottawa, Author, 1986).

The trends that can cause the rise have been noted earlier, including an actual rise in disability, the increased life expectancies of persons with disabilities and the survival of persons who might have otherwise died and now survive with a disability. However, there are probably socio-cultural explanations for the rise. As disability advocates stress the human rights of persons with disabilities, persons may be more willing to report themselves as disabled. Note also, as shown in figure 10, the prevalence rates reported for children 10 to 14 years of age are higher than for persons 15 to 34. This suggests a social issue: children may be identified as disabled in the school situation but not in adult situations. Perhaps as learning disabilities gain more attention, persons may be more willing to identify themselves as disabled throughout their lives. Another important explanation of the rise in Canada for adults with disabilities may be found within the age categories. For example, just as the Canadian population overall is aging, there may also be a trend towards aging within some categories (i.e., as life expectancy increases, those 85 and over constitute a greater proportion of the population 65 years of age and over). This within-category aging would then contribute to an increase in disability for the 65 and over category.

As indicators are examined, caution is advised even in a time series of the quality of Canada's. For example, an examination of the gender composition of children over time raises some concerns. When gender ratios are calculated by dividing the number of boys by the number of girls and multiplying the results by 100, the results as given in figure 12 show a great deal of volatility over time within the five year age groupings. Not only does this volatility occur across time but also across cohort. As the children under 5 years of age grew older between 1986 and 1991, their gender ratio increased. In 1986, girls constituted the majority of disabled children under 5 but by 1996, boys constituted a majority of these children when they were 5 to 9. However, as the children who were 5 to 9 in 1986 became 10 to 14 in 1991, their gender ratio decreased. If indicators are at all tied to gender, then changes that occur over time could be due to changes in the sex composition of children with disabilities.

This problem is dramatized by the Tunisian data for adults 15 years of age and over, as well. Despite the relative similarity of categories, the number of women reported with disabilities in 1975 was extremely low. Between 1975 and 1994, while the number of disabled men reported more than doubled, the number of disabled women reported grew by many more times. As shown in figure 12, this resulted in the percentage of women in the disabled population tripling between 1975 and 1994. (Actually, the data demonstrate this change primarily occurred between 1975 and 1984.) There are many reasons to speculate as to whether disabled women were undercounted in 1975. Whether the change is real or a statistical artifact, it can clearly influence outcomes that are associated with gender.

Note: Sex ratios are calculated by dividing the number of boys by the number of girls and multiplying the result by 100.

Sources: Statistics Canada, Health Division and Department of the Secretary of State, Social trends analysis directorate, 1986; report of the Canadian health and disability survey, 1983-84 (Ottawa, Author, 1986); Avard, Denise, Children and Youth with Disabilities in Canada: the 1986 health and activity limitation survey (Ottawa, Statistics Canada, 1996), Appendix A, p. 58, Table 2; and Children and Youth with Disability, Chapter 8 in The Health of Canada's Children: a CICH profile (Ottawa, Canadian Institute of Child Health, 1997), Table VIII.1.

Sources: Tunisia, Institut national de la statistique, Recensement general de la population et des logements, 8 Mai 1975, Volume III, Caracteristiques demographiques, tableaux et analyses des resultats du sondage au 1/10eme75 (Tunis, Author, 1975).

Notes:

[170] See United Nations Disability Statistics Data Base …., Table A.1, "Countries or areas that collected national disability statistics …", pp 27-29.