Bias: practice question

The best answer is D, Systematic difference in how participants are chosen. The defining Bias principle supports Systematic difference in how participants are chosen; it directly accounts for the forensic observation, evidence requirement, or public-health measure in the question.

Error from lab equipment only may be useful elsewhere but is not the best answer here.

Effect of prevalence on predictive value is not consistent with the finding or appropriate action described.

Random variation around a mean does not establish the requested bias conclusion.

It tests Bias in PSM. The correct option holds because: Correct. Systematic difference in how participants are chosen best fits the important clue in this sample.

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

Practise biostatistics with small calculations until sensitivity, predictive values and risk measures are automatic. Then use the flashcards and the other PSM questions on this site to test what stuck.

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.