Undercoverage acts at which boundary?

Answer

Between the target and the study population

Options - A. Between the target and the study population - B. Between the study population and the sample that was measured - C. Between the sample and the recorded measurement - D. It is a form of measurement bias Why - A. Correct — the frame (study population) fails to include part of the target; nobody in the missing part can be drawn. - B. That boundary is where non-response and self-selection act: units in the frame that do not end up measured. - C. That is measurement bias — the recorded value differs from the true one. - D. Undercoverage is about who can be drawn, not about how a value is recorded.

S21 W1 handout (three-layer taxonomy, shape only); IBS1 §1.2 (bias list; "size is not representativeness", CC BY 4.0); original scenarios