MCAT Math Question 21: Answer and Explanation

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Question: 21

6. After randomization, it is discovered that one group in a study has almost twice as many women as the other. Which of the following is an appropriate response?

  • A. Move men and women between groups manually so that they have the same gender profile.
  • B. Check the randomization algorithm; if it is fair, continue with the research.
  • C. Eliminate all of these subjects because of potential bias and randomize a new cohort.
  • D. Keep the current cohort and continue randomizing subjects until the gender profiles are equal.

Correct Answer: B

Explanation:

Randomization is based on the idea that the results will only vary as a result of random chance as long as the assignment is proper. The appropriate response to a fair algorithm that assigns groups in an unexpected way is to proceed with the research. Participants should never be assigned by the researcher, nor should one continue randomizing samples to achieve a desired outcome—these are likely to introduce more error than leaving unequal groups, eliminating choices (A) and (D). It is unnecessary to drop this entire cohort, assuming the randomization algorithm was fair, eliminating choice (C).

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