Selection and recall bias vs Lead-time, length-time, and confounding bias
How to tell Selection and recall bias and Lead-time, length-time, and confounding bias apart when a board question makes them look alike.
Selection/recall distort who enters or remembers; lead/length distort screening survival; confounding is a lurking third variable.
Side by side
Selection bias arises from nonrepresentative enrollment or follow-up; recall bias occurs when cases remember exposures differently than controls.
Lead-time bias makes earlier diagnosis appear to improve survival; length-time bias overdetects slow disease; confounding is a third variable linked to exposure and outcome.
Selection bias arises from nonrepresentative enrollment or follow-up; recall bias occurs when cases remember exposures differently than controls.
Lead-time bias makes earlier diagnosis appear to improve survival; length-time bias overdetects slow disease; confounding is a third variable linked to exposure and outcome.
The repair move
Before naming the answer, force the stem through the separator: Selection/recall distort who enters or remembers; lead/length distort screening survival; confounding is a lurking third variable.
Try a free question
CoreIn a case-control study of bladder cancer and smoking, patients with bladder cancer recall and report their smoking history more carefully and accurately than controls without cancer (who may forget or underestimate). The cases also tend to overreport occupational exposures they wonder might have caused their disease. Which bias is this?
Show answer and explanation
Answer: A. Recall bias. Recall bias occurs when cases (who have disease) remember and report exposures differently than controls (who don't have disease). Cases often recall more carefully and may overreport exposures they suspect caused disease. This is the classic limitation of CASE-CONTROL studies. Mitigate by using objective measures (medical records, biomarkers) rather than self-report when possible.
Why the other choices are tempting
- B. Lead-time bias makes earlier diagnosis appear to improve survival in screening studies.
- C. Length-time bias overrepresents slow-growing disease in screening.
- D. Confounding is a third variable linked to both exposure and outcome.
- E. Berkson bias is selection bias arising from hospital-based controls.
Flashcards
Tap a card to flip it.
What clue supports Selection and recall bias?
Choose Selection and recall bias when the stem gives this pattern: Selection bias arises from nonrepresentative enrollment or follow-up; recall bias occurs when cases remember exposures differently than controls.
What clue supports Lead-time, length-time, and confounding bias?
Choose Lead-time, length-time, and confounding bias when the stem gives this contrasting pattern: Lead-time bias makes earlier diagnosis appear to improve survival; length-time bias overdetects slow disease; confounding is a third variable linked to exposure and outcome.
Quick answers
What is the fastest way to tell Selection and recall bias from Lead-time, length-time, and confounding bias?
Selection/recall distort who enters or remembers; lead/length distort screening survival; confounding is a lurking third variable.
What is the key clue for Selection and recall bias?
Selection bias arises from nonrepresentative enrollment or follow-up; recall bias occurs when cases remember exposures differently than controls.
What is the key clue for Lead-time, length-time, and confounding bias?
Lead-time bias makes earlier diagnosis appear to improve survival; length-time bias overdetects slow disease; confounding is a third variable linked to exposure and outcome.