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PSM · Epidemiology: non-response bias
Sample itemA household survey on tobacco use in a district achieves a response of only 55 percent. The non-respondents are mostly young men away at work, who smoke more than the people interviewed, so the prevalence estimate is too low. Which bias is this?
Original practice item, not a recalled exam question. Nothing here is recorded.
The answer and the reasoning
B. Non-response bias
Non-response bias occurs when people who do not take part differ systematically from those who do, so the sample no longer represents the population. It can be reduced by repeat visits, substitution rules and weighting.
Option by option
A. Interviewer bias
Interviewer bias arises from how the interviewer asks or records answers, which is not described.
B. Non-response bias (correct)
Correct. Respondents and non-respondents differ in smoking, so the sample estimate is biased.
C. Recall bias
Recall bias arises from differences in remembering past exposures between groups.
D. Misclassification bias
Misclassification bias arises from wrongly labelling exposure or disease status in those who are studied.
Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.
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