100% Pass
Which of the following types of bias is most commonly associated with a case-control
study? - ✔✔Recall bias
A new non-invasive screening test is proposed that is claimed to be able to identify
patients with impaired glucose tolerance based on a battery of questions related to
health behaviors. The new test is given to 75 patients. Based on each patient's responses
to the questions they are classified as positive or negative for impaired glucose
tolerance. Each patient also submits a blood sample and their glucose tolerance status is
determined. The results are tabulated below
What is the sensitivity of the screening test?
What is the false positive fraction of the screening test? - ✔✔Sensitivity = #(true
positives)/(#(true positives)+#(false negatives)) = 17/(17+8) = 17/25 = 0.68
Answer: 0.68
Brittie Donald, All Rights Reserved © 2025 1
, False positive fraction = #(false positives)/(#(false positives)+#(true negatives))
=13/(13+37)
= 13/50 = 0.26
Answer: 0.26
A study is designed to evaluate the impact of a daily multivitamin on students'
academic performance. One hundred sixty students are randomly assigned to receive
either the multivitamin or a placebo and are instructed to take the assigned drug daily
for 20 days. On day 20, each student takes a standardized exam and the mean exam
scores are compared between groups. This study is an example of a - ✔✔Randomized
Control Trial
When estimating sample size, it is not important for researchers to account for attrition
or loss of participants during follow-up. - ✔✔True
Five hundred people are enrolled in a 10-year cohort study. At the start of the study, 50
have diagnosed CVD. Over the course of the study, 40 people who were free of CVD at
baseline develop CVD. What is the cumulative incidence of CVD over 10 years? - ✔✔A.
Cumulative incidence of CVD over 10 years
Cumulative incidence 40/450=.0888 x 100=8.9%
B. The prevalence of CVD at base line
a. Prevalence baseline=50/500 .1 x 100= 10%
Brittie Donald, All Rights Reserved © 2025 2