QUESTION 1
Researchers applied a new rapid screening test to detect Hepatitis C in a group of injection drug
users. It is known that the prevalence of Hepatitis C in this group is 25%. The sensitivity and
specificity of the screening test is found to be 95% and 88% respectively. Researchers use ...
QUIZ 3-6003-KEY
QUESTION 1
Researchers applied a new rapid screening test to detect Hepatitis C in a group of injection drug users. It is known that the prevalence of Hepatitis C in this group is 25%. The sensitivity and specificity of the screening test is found to be 95% and 88% respectively. Researchers use the screening test in a low risk group of college students who are thought to have a 1% prevalence of Hepatitis C. Which of the folllowing statements are true?
A.Sensitivity and specificity will decrease.
B.Positive predictive value will decrease.
C.Sensitivity, specificity and positive predictive value will increase.
D.Positive predictive value will increase.
Positive predictive value will decrease. Lower prevalence settings result in lower PPV. Sensitivity and specificity don't change based on setting.
QUESTION 2
Scientists have discovered a new virus called Virus X. The virus must be preset to cause a new type of influenza. Everyone who is infected with virus X presents with the new type of influenza
without any additional contributing factors. In other words, virus X alone can cause the new type of influenza. Virus X can be classified as which of the following: A.Necessary and sufficient cause
B.Neither necessary nor sufficient
C.Necessary but not sufficient
D.Sufficient but not necessary
Necessary=virus must be present for disease. Sufficient=no other contributing factors and everyone with infection gets disease
QUESTION 3
A long term follow up of men who were screened for prostate cancer found that men who used a new screening program were identified as having prostate cancer much earlier and survived longer than men who were identified using the traditional screening methods. Men decided on their own whether to be screened or not and were not randomized. Which of the following explanations is most likely?
A.This is an example of lead time bias.
B.This is an example of confounding.
C.The new screening program is definitely effective in prolonging the lives of men with This study source was downloaded by 100000842568006 from CourseHero.com on 08-13-2022 16:29:27 GMT -05:00
https://www.coursehero.com/file/52150968/Quiz-3-Keydocx/
PUBH 6003 QUIZ 3 KEY QUESTIONS AND ANSWERS 2022 prostate cancer.
D.This is an example of volunteer bias.
They were not randomized to screening or no screening. The screening did not actually improve the length of time survived. The men were just diagnosed with prostate cancer earlier, but they still died at the same time they would have with a later diagnosis.
QUESTION 4
An article was recently published on the relationship between caffeine consumption during pregnancy and low birth weight. The article was based on the results of a prospective cohort study. As you know, caffeine is present in a wide variety of beverages, foods, and medications, including coffee, tea, and colas. Select the Hill’s guideline for causality that best describes this statement. Each term is used only once.
In the current study, there was a four-fold increased risk (RR=4.0) of giving birth to a low birth weight infant among women who drank caffeine during pregnancy compared to women who did not consume any caffeine during pregnancy.
A.Biologic plausibility
B.Effect modification
C.Dose response
D.Strength of association
QUESTION 5
VDRL is a screening test for syphilis. If we say "One fifth of those with syphilis will have a normal
(negative) VDRL test", the one fifth refers to the people who are?
A.True negatives
B.False negatives
C.False positives
D.True positives
FALSE NEGATIVES BECAUSE HAVE SYPHILIS BUT NEGATIVE TEST
QUESTION 6
Which of the following is not a characteristic of a confounding variable?
A.A confounder is associated with the outcome.
B.A confounder is associated with the exposure.
C.The measure of association varies by different levels of the confounding variable .
This study source was downloaded by 100000842568006 from CourseHero.com on 08-13-2022 16:29:27 GMT -05:00
https://www.coursehero.com/file/52150968/Quiz-3-Keydocx/
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