Study designs Practice Questions

Question 1

A researcher is studying whether a new knee implant is better than existing alternatives in terms of pain after knee replacement. She designs the study so that it includes all the surgeries performed at a certain hospital. Interestingly, she notices that patients who underwent surgeries on Mondays and Thursdays reported much better pain outcomes on a survey compared with those who underwent the same surgeries from the same surgeons on Tuesdays and Fridays. Upon performing further analysis, she discovers that one of the staff members who works on Mondays and Thursdays is aware of the study and tells all the patients about how wonderful the new implant is. Which of the following forms of bias does this most likely represent?

Accepted Answer

Pygmalion effect

Answer

Hawthorne effect

Answer

Attrition bias

Answer

Golem effect

Question 2

A 42-year-old woman presents to the physician with symptoms of vague abdominal pain and bloating for several months. Test results indicate that she has ovarian cancer. Her physician attempts to reach her by phone multiple times but cannot reach her. Next of kin numbers are in her chart. According to HIPAA regulations, who should be the primary person the doctor discusses this information with?

Accepted Answer

The patient

Answer

The patient's brother

Answer

The patient's husband

Answer

The patient's daughter

Answer

All of the options

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

A researcher is trying to determine whether a newly discovered substance X can be useful in promoting wound healing after surgery. She conducts this study by enrolling the next 100 patients that will be undergoing this surgery and separating them into 2 groups. She decides which patient will be in which group by using a random number generator. Subsequently, she prepares 1 set of syringes with the novel substance X and 1 set of syringes with a saline control. Both of these sets of syringes are unlabeled and the substances inside cannot be distinguished. She gives the surgeon performing the surgery 1 of the syringes and does not inform him nor the patient which syringe was used. After the study is complete, she analyzes all the data that was collected and performs statistical analysis. This study most likely provides which level of evidence for use of substance X?

Accepted Answer

Level 1

Answer

Level 3

Answer

Level 4

Answer

Level 5

Answer

Level 2

Question 5

A pharmaceutical corporation has asked you to assist in the development of a randomized controlled trial (RCT) to evaluate the response of renal cell carcinoma to a novel chemotherapeutic agent. Despite all of the benefits that an RCT has to offer, which of the following would make an RCT unacceptable with regard to study design?

Accepted Answer

The treatment has a known, adverse outcome

Answer

Proper treatment response is very common

Answer

The treatment is not widespread in use

Answer

The treatment does not represent the best known option

Answer

The treatment is expensive

Question 6

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 7

A 28-year-old male presents to his primary care physician with complaints of intermittent abdominal pain and alternating bouts of constipation and diarrhea. His medical chart is not significant for any past medical problems or prior surgeries. He is not prescribed any current medications. Which of the following questions would be the most useful next question in eliciting further history from this patient?

Accepted Answer

"Can you tell me more about the symptoms you have been experiencing?"

Answer

"Does the diarrhea typically precede the constipation, or vice-versa?"

Answer

"Is the diarrhea foul-smelling?"

Answer

"Please rate your abdominal pain on a scale of 1-10, with 10 being the worst pain of your life"

Answer

"Are the symptoms worse in the morning or at night?"

Question 8

A 73-year-old man is brought to the emergency department by ambulance after being found to be non-communicative by his family during dinner. On presentation he appears to be alert, though he is confused and cannot follow instructions. When he tries to speak, he vocalizes a string of fluent but unintelligible syllables. Given this presentation, his physician decides to administer tissue plasminogen activator to this patient. This intervention best represents which of the following principles?

Accepted Answer

This does not represent prevention

Answer

Tertiary prevention

Answer

Primary prevention

Answer

Quaternary prevention

Answer

Secondary prevention

Question 9

A research team has data from three completed studies on statin use and Alzheimer's disease: Study A (case-control, OR=0.6, n=500), Study B (retrospective cohort, RR=0.7, n=10,000), and Study C (RCT with cognitive decline as secondary endpoint, RR=0.9, n=2,000). The case-control study used prevalent cases, the cohort study had significant loss to follow-up in the unexposed group, and the RCT was underpowered for cognitive outcomes. Synthesize the evidence to determine the most reliable conclusion about the association.

Accepted Answer

The retrospective cohort study offers the best balance of validity and precision

Answer

The RCT provides the strongest evidence despite being underpowered

Answer

Case-control study is most reliable due to efficient rare outcome assessment

Answer

Evidence is contradictory and no conclusion can be drawn

Answer

Meta-analysis of all three studies provides the most accurate estimate

Question 10

A public health department needs to determine whether a cluster of birth defects in a county is associated with industrial pollution. They have limited resources, the suspected exposure occurred 3-5 years ago, and the outcome is rare (15 cases identified). Multiple potential confounders exist including maternal age, socioeconomic status, and prenatal care access. The community demands rapid answers. Evaluate the most appropriate initial study design considering feasibility, ethics, and scientific validity.

Accepted Answer

Case-control study with multiple control groups and confounder adjustment

Answer

Prospective cohort study of pregnant women with exposure monitoring

Answer

Randomized controlled trial comparing exposed and unexposed areas

Answer

Ecologic study comparing county-level pollution and birth defect rates

Answer

Cross-sectional survey of current pollution levels and birth outcomes

Study designs

Study Resources

Lessons

Questions

Flashcards

Lessons

Observational studies vs experiments

Cross-sectional studies

Case-control studies

Cohort studies

Randomized controlled trials

Meta-analyses and systematic reviews

Qualitative research methods

Survey design

Sampling methods

Blinding and controls

Bias identification and mitigation

Confounding variables

Practice Questions

Flashcards

About Study designs for USMLE

Lessons in Study designs

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