A Guide to HIV/AIDS Epidemiological and Surveillance Terms
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Frequently Used Terms in HIV/AIDS Monitoring and
Epidemiological Research in Canada
(Refer to DEMOGRAPHICS)
The term demographics is commonly used to describe the personal
characteristics of a population or specific group. These
characteristics can include information describing age, gender,
occupation and ethnicity. Demographics do not include a
|For example, individual outpatient interviews were used to
collect personal information from HIV-positive outpatients
identified through the HIV Ontario Observational Database (HOOD).
The interview included questions about the participant's
gender, age, income, education, and employment status. This
demographic information was used to determine whether there were
differences in the characteristics of those outpatients who used
antiretroviral medication and those who did not use such
medication. (Furler et al., 2001)
A "demographic profile" characterizes a population or
a specific group of people in terms of current demographic
|Researchers have reported the following demographic profile of
a group of 229 young adult injecting drug users in Baltimore,
Maryland: "The median age was 23.5 years
(range 18-29 years);
79% were of African-American ethnicity; 54% were female; and 61%
had not completed high school or obtained a high school
equivalency." (Garfein et al., 1998)
The denominator is the bottom number in a
fraction, and the numerator is the top number. The
fraction can be used to calculate a proportion or rate.
The denominator usually represents a population group or a group
of people at risk of a specific disease (population at risk). In
the numerator usually represents the number of people in the
population at risk who are affected by a specific event.
For example, at the end of 1999 there were an estimated 49,800
people in Canada living with HIV infection (including those living
with AIDS). Of these people, 6,800 were estimated to be women.
(Bureau of HIV/AIDS, STD and TB, Centre for Infectious Disease
Prevention and Control, Health Canada, 2001a)
Using this information in the numerator and demoninator, we can
calculate how much of the estimated Canadian population with
HIV/AIDS are women:
of women with HIV/AIDS
||estimate of all Canadians with HIV/AIDS
| = 0.1365
This means that at the end of 1999 approximately 13.65% (0.1365
× 100) of the estimated Canadian population with HIV/AIDS are
Descriptive statistics are used to organize and describe data.
range are examples of
|For example, here are the ages of 12 women who tested positive
for HIV in 2001 with no descriptive statistics applied:
18, 23, 27, 34, 21, 31, 36, 23, 19, 42, 32,
As can be seen, it is difficult, if not impossible, to determine
general trends until
some order is applied to the data. Applying descriptive statistics
will tell you much more about the data.
|If we calculate the mean in the example above, we would know
that the mean, or more commonly average, age of the 12 women who
tested positive for HIV in 2001 was 28 years.
Examples of descriptive statistics can be found under the terms
mean, median, mode and range.
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