Today’s question will test your understanding of an important, commonly tested biostatistics principle.
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A clinical trial is being conducted to compare the efficacy of two antihypertensive medications, Drug A and Drug B, in lowering blood pressure in patients with newly diagnosed hypertension. The primary outcome is the change in systolic blood pressure after 12 weeks of treatment. The study aims to minimize potential biases and ensure that the two treatment groups are similar in terms of relevant baseline characteristics. Which of the following best describes the primary purpose of randomization in this clinical trial?
A) To establish causality between the intervention and the outcome
B) To control for confounding variables
C) To reduce the impact of selection bias
D) To minimize measurement errors in blood pressure readings
E) To control for potential placebo effects
F) To prevent observer bias in assessing treatment outcomes
G) To ensure equal sample sizes in each treatment group
Detailed Breakdown of Answers + Correct Answer Below ⏬
ANSWER + QUESTION BREAKDOWN
The MENTAL MODEL used to answer this question comes from our detailed test-taking skills masterclass (check it out if you want to elevate your skills). Here’s how to think through this question:
Step 1. Read the last line to determine the actual question: “Which of the following best describes the primary purpose of randomization in this clinical trial?”
Step 2: Is this a first-, second-, or third-order question?
Answer: 2nd order. 1st: Identify the issue with the clinical trial, and 2nd: Make a connection between the trial’s issue and how randomization addresses it.
Step 3: Read the vignette carefully and ask yourself: “Why is randomization helpful in this scenario?”
Step 4. Look at the answer choices and select the option most closely resembling your final thought from “Step 3” above.
GENERAL ANALYSIS
The primary purpose of randomization in a clinical trial is to ensure that the treatment groups are comparable, thereby controlling for confounding variables. This helps ensure that any differences in outcomes can be attributed to the treatments being tested rather than other factors.
ANSWER CHOICES:
CHOICE A: To establish causality between the intervention and the outcome
Explanation: Randomization helps establish causality by ensuring that outcome differences are due to the intervention, not confounding factors. The primary purpose of randomization is to control confounding variables, which supports causal inference but is not solely about establishing causality.
CHOICE B: To control for confounding variables
Explanation: Randomization evenly distributes known and unknown confounding variables across treatment groups. This is the primary purpose of randomization, ensuring that any differences in outcomes can be attributed to the treatment rather than other factors.
CHOICE C: To reduce the impact of selection bias
Explanation: Randomization helps prevent selection bias by giving each participant an equal chance of being assigned to any group. While it reduces selection bias, the primary goal is controlling confounding.
CHOICE D: To minimize measurement errors in blood pressure readings
Explanation: Measurement errors are addressed through standardized procedures and equipment calibration. Randomization does not directly address measurement errors.
CHOICE E: To control for potential placebo effects
Explanation: Placebo effects are controlled through blinding and placebo controls. Randomization itself does not control placebo effects.
CHOICE F: To prevent observer bias in assessing treatment outcomes
Explanation: Observer bias is minimized by blinding participants and researchers. Randomization does not address observer bias directly.
CHOICE G: To ensure equal sample sizes in each treatment group
Explanation: Randomization can lead to similar group sizes by chance but does not guarantee equal sizes. Ensuring equal sample sizes is not the primary goal of randomization.
FINAL VERDICT…
Randomization involves randomly assigning participants to different treatment groups. This helps distribute known and unknown confounding variables evenly across the groups. By minimizing confounding, randomization increases the study's internal validity, allowing for a clearer interpretation of the causal relationship between the intervention and the outcome.
CORRECT ANSWER: B) To control for confounding variables
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That’s it for question 78!
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