HLTH 503 Final UPDATED ACTUAL Questions and CORRECT Answers
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Course
HLTH 503
Institution
HLTH 503
HLTH 503 Final UPDATED ACTUAL
Questions and CORRECT Answers
True or False? Reliability refers to the ability of a measuring instrument to give consistent
results on repeated trials, regardless of its accuracy. - CORRECT ANSWER- True
A new screening test for Lyme disease is developed for use i...
HLTH 503 Final UPDATED ACTUAL
Questions and CORRECT Answers
True or False? Reliability refers to the ability of a measuring instrument to give consistent
results on repeated trials, regardless of its accuracy. - CORRECT ANSWER✔✔- True
A new screening test for Lyme disease is developed for use in the general population. The
sensitivity and specificity of the new test are 60% and 70%, respectively. Three hundred
people are screened at a clinic during the first year the new test is implemented. Assume the
true prevalence of Lyme disease among clinic attendees is 10%.
Calculate the following value
The predictive value of a positive test is: - CORRECT ANSWER✔✔- 18.2%
True or False? Sensitivity refers to the ability of a screening test to correctly identify all
screened individuals who have a disease. - CORRECT ANSWER✔✔- True
A new antibody test detects serum antibodies against virus X (sensitivity 99%, specificity
90%). When applied in a group of hospitalized patients diagnosed as having virus X
infections, the test is found to have a positive predictive value of 85%. When used to screen a
group of healthy blood donors for virus X infections, the test is found to have a positive
predictive value of 30%. Which of the following best explains this difference between the
positive predictive values? - CORRECT ANSWER✔✔- The prevalence of virus X infection
is higher among the hospital patients than among blood donors
True or False? Specificity refers to the ability of a screening test to identify only nondiseased
individuals who actually do not have the disease. - CORRECT ANSWER✔✔- True
A new screening test for Lyme disease is developed for use in the general population. The
sensitivity and specificity of the new test are 60% and 70%, respectively. Three hundred
people are screened at a clinic during the first year the new test is implemented. Assume the
true prevalence of Lyme disease among clinic attendees is 10%.
Calculate the following value
The number of false positives is: - CORRECT ANSWER✔✔- 81
,The degree of agreement among several trained experts refers to: - CORRECT
ANSWER✔✔- inter-judge reliability
A screening examination was performed on 250 persons for Factor X, which is found in
disease Y. A definitive diagnosis for disease Y among the 250 persons had been obtained
previously. The results are charted below: The sensitivity of this test is expressed as: -
CORRECT ANSWER✔✔- 80%
Sensitivity and specificity of a screening test refer to its: - CORRECT ANSWER✔✔-
Validity
True or False? Validity is the ability of a measuring instrument to give a true measure. -
CORRECT ANSWER✔✔- True
A test that determines whether disease is actually present is a: - CORRECT ANSWER✔✔-
diagnostic test
A screening examination was performed on 250 persons for Factor X, which is found in
disease Y. A definitive diagnosis for disease Y among the 250 persons had been obtained
previously. The results are charted below: The specificity of this test is expressed as: -
CORRECT ANSWER✔✔- 70%
True or False? Incubation period refers to the time between the start of an infection and the
beginning of the period of communicability. - CORRECT ANSWER✔✔- False
True or False? Herd immunity must be 100% to confer protection to a group. - CORRECT
ANSWER✔✔- False
True or False? The presence of an infectious agent is a sufficient cause for outbreaks of
infectious disease to occur. - CORRECT ANSWER✔✔- False
An attack rate is an alternative incidence rate that is used when: - CORRECT ANSWER✔✔-
All the above
, Schistosomiasis is an example of: - CORRECT ANSWER✔✔- biological agents-helminth
True or False? An enzootic disease among animals is similar to an endemic disease among
humans. - CORRECT ANSWER✔✔- True
A person with an inapparent infection: - CORRECT ANSWER✔✔- can transmit the infection
to others
True or False? Antigenicity of an infectious agent is measured by the secondary attack rate. -
CORRECT ANSWER✔✔- False
Which of the following examples involves indirect transmission of disease? - CORRECT
ANSWER✔✔- A and B
True or False? Physical environmental factors in the natural history of disease include
weather, temperature, and biologic components. - CORRECT ANSWER✔✔- False
True or False? If a disease is fatal, virulence can be measured by the case fatality rate. -
CORRECT ANSWER✔✔- True
An outbreak of salmonellosis occurred after an epidemiology department luncheon, which
was attended by 485 faculty and staff. Assume everyone ate the same food items. Sixty-five
people had fever and diarrhea, five of these people were severely affected. Subsequent
laboratory tests on everyone who attended the luncheon revealed an additional 72 cases.
The attack rate of salmonellosis was: - CORRECT ANSWER✔✔- 28.2%
What factors comprise the epidemiologic triangle? - CORRECT ANSWER✔✔- All of the
above
The death rate per 100,000 for lung cancer is 7 among non-smokers and 71 among smokers.
The death rate per 100,000 for coronary thrombosis is 422 among non-smokers and 599
among smokers. The prevalence of smoking in the population is 55%.
The population etiologic fraction of disease due to smoking is: - CORRECT ANSWER✔✔-
0.83 for lung cancer and 0.18 for coronary thrombosis.
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