Study Design Practice Questions

Question 1

A study is funded by the tobacco industry to examine the association between smoking and lung cancer. They design a study with a prospective cohort of 1,000 smokers between the ages of 20-30. The length of the study is five years. After the study period ends, they conclude that there is no relationship between smoking and lung cancer. Which of the following study features is the most likely reason for the failure of the study to note an association between tobacco use and cancer?

Accepted Answer

Latency period

Answer

Late-look bias

Answer

Confounding

Answer

Effect modification

Answer

Pygmalion effect

Question 2

A research team develops a new monoclonal antibody checkpoint inhibitor for advanced melanoma that has shown promise in animal studies as well as high efficacy and low toxicity in early phase human clinical trials. The research team would now like to compare this drug to existing standard of care immunotherapy for advanced melanoma. The research team decides to conduct a non-randomized study where the novel drug will be offered to patients who are deemed to be at risk for toxicity with the current standard of care immunotherapy, while patients without such risk factors will receive the standard treatment. Which of the following best describes the level of evidence that this study can offer?

Accepted Answer

Level 3

Answer

Level 1

Answer

Level 5

Answer

Level 4

Answer

Level 2

Question 3

A researcher is conducting a study to compare fracture risk in male patients above the age of 65 who received annual DEXA screening to peers who did not receive screening. He conducts a randomized controlled trial in 900 patients, with half of participants assigned to each experimental group. The researcher ultimately finds similar rates of fractures in the two groups. He then notices that he had forgotten to include 400 patients in his analysis. Including the additional participants in his analysis would most likely affect the study's results in which of the following ways?

Accepted Answer

Increased probability of rejecting the null hypothesis when it is truly false

Answer

Wider confidence intervals of results

Answer

Increased probability of committing a type II error

Answer

Decreased significance level of results

Answer

Increased external validity of results

Question 4

You are reading through a recent article that reports significant decreases in all-cause mortality for patients with malignant melanoma following treatment with a novel biological infusion. Which of the following choices refers to the probability that a study will find a statistically significant difference when one truly does exist?

Accepted Answer

Power

Answer

Type II error

Answer

Type I error

Answer

Confidence interval

Answer

p-value

Question 5

Which of the following study designs would be most appropriate to investigate the association between electronic cigarette use and the subsequent development of lung cancer?

Accepted Answer

Subjects who smoke electronic cigarettes and subjects who do not smoke

Answer

Subjects with lung cancer who smoke and subjects with lung cancer who did not smoke

Answer

Subjects who smoke electronic cigarettes and subjects who smoke normal cigarettes

Answer

Subjects with lung cancer who smoke and subjects without lung cancer who smoke

Answer

Subjects with lung cancer and subjects without lung cancer

Question 6

The APPLE study investigators are currently preparing for a 30-year follow-up evaluation. They are curious about the number of participants who will partake in follow-up interviews. The investigators noted that of the 83 participants who participated in the APPLE study's 20-year follow-up, 62 were in the treatment group and 21 were in the control group. Given the unequal distribution of participants between groups at follow-up, this finding raises concerns for which of the following?

Accepted Answer

Attrition bias

Answer

Volunteer bias

Answer

Reporting bias

Answer

Inadequate sample size

Answer

Lead-time bias

Question 7

You are interested in studying the etiology of heart failure reduced ejection fraction (HFrEF) and attempt to construct an appropriate design study. Specifically, you wish to look for potential causality between dietary glucose consumption and HFrEF. Which of the following study designs would allow you to assess for and determine this causality?

Accepted Answer

Cohort study

Answer

Cross-sectional study

Answer

Case series

Answer

Case-control study

Answer

Randomized controlled trial

Question 8

A population is studied for risk factors associated with testicular cancer. Alcohol exposure, smoking, dietary factors, social support, and environmental exposure are all assessed. The researchers are interested in the incidence and prevalence of the disease in addition to other outcomes. Which pair of studies would best assess the 1. incidence and 2. prevalence?

Accepted Answer

1. Prospective cohort study 2. Cross sectional study

Answer

1. Prospective cohort study 2. Retrospective cohort study

Answer

1. Cross sectional study 2. Retrospective cohort study

Answer

1. Case-control study 2. Prospective cohort study

Answer

1. Clinical trial 2. Cross sectional study

Question 9

Many large clinics have noticed that the prevalence of primary biliary cholangitis (PBC) has increased significantly over the past 20 years. An epidemiologist is working to identify possible reasons for this. After analyzing a series of nationwide health surveillance databases, the epidemiologist finds that the incidence of PBC has remained stable over the past 20 years. Which of the following is the most plausible explanation for the increased prevalence of PBC?

Accepted Answer

Improved quality of care for PBC

Answer

Increased availability of diagnostic testing for PBC

Answer

Increased exposure to environmental risk factors for PBC

Answer

Increased awareness of PBC among clinicians

Answer

Increased average age of the population at risk for PBC

Question 10

A patient is in the ICU for diabetic ketoacidosis and is currently on an insulin drip. His electrolytes are being checked every hour and his potassium is notable for the following measures:

1. 5.1 mEq/L
2. 5.8 mEq/L
3. 6.1 mEq/L
4. 6.2 mEq/L
5. 5.9 mEq/L
6. 5.1 mEq/L
7. 4.0 mEq/L
8. 3.1 mEq/L

Which of the following is the median potassium value of this data set?

Accepted Answer

5.45

Answer

6.05

Answer

5.10

Answer

5.16

Answer

3.10

Study Design

Study Resources

Lessons

Questions

Flashcards

Lessons

Research question formulation

Case-control studies

Cross-sectional studies

Ecological studies

Quasi-experimental designs

Natural experiments

N-of-1 trials

Mixed methods research

Qualitative study designs

Sampling techniques

Matching methods

Longitudinal vs cross-sectional approaches

Multi-center studies

Pilot and feasibility studies

Practice Questions

Flashcards

About Study Design for USMLE

Lessons in Study Design

Master Study Design