HEPI3 – Week 4 Assignment
This assignment is worth 9% of your course total mark.
NOTE: You MUST show all calculation
steps, and when necessary, explain why you are taking those steps. If your
steps are correct but you arrive at an incorrect answer, you will still earn
some points.
1 Assume
that 8 people out of a community of 800 are ill with disease X, and the
horizontal lines in the diagram below represent duration of illness in those 8
people.
Calculate
the following measures:
a.
Point prevalence of the disease on July 1
b.
Point prevalence of the disease on August 1
c. Period prevalence
of the disease during July
d.
Incidence rate of the disease in July
2
In city X, 1812 individuals developed prostate
cancer in 2012. Population of the city was estimated to be 2,210,600 on July 1,
2012. Calculate the incidence rate (per 10,000) for prostate cancer for the
city.
Hint:
Except in extreme cases, for example is the case of a city where a lot of males
have been killed in the war, or in a small city built close to a mine where
most people are miners, you can always assume that numbers of males and females
are almost equal. This is due to the fact that when a sperm attaches to an egg,
there is exactly 50% chance that the sperm carries female genes and 50% chance
that it carries male genes.
Hint2:
Note that some diseases can only develop in one gender.
3
In a study on incidence rate of disease X, that
involved observing 8 participants over 5 years, 2 of the participants died
after 2 years, one quit the study after 3 years, and one became ill with
disease X after 4 years. How many personyears of observation were done at the
end of the study?
4
A prevalence study in 2012 identified 2,320
cases of malaria in a city of 3.3 million people in Asia. If the incidence rate
is 12 per 100,000 persons per year, what percentage of the 2,320 cases were
newly developed in 2012?
NOTE: You MUST show all calculation
steps, and when necessary, explain why you are taking those steps. If your
steps are correct but you arrive at an incorrect answer, you will still earn
some points.
1
A diagnostic test was performed on
2450 individuals. The test incorrectly identified as positive 420
healthy individuals, and incorrectly identified as negative 39
patients.258 people indeed have the disease. Calculate the following measures:

Sensitivity

Specificity

Positive predictive value

Negative predictive value

Point prevalence