The relative impact of interviewer effects and sample design effects on survey precision

One of the principal sources of error in data collected from structured face-to-face interviews is the interviewer. The other major component of imprecision in survey estimates is sampling variance. It is rare, however, to find studies in which the complex sampling variance and the complex interviewer variance are both computed. This paper compares the relative impact of interviewer effects and sample design effects on survey precision by making use of an interpenetrated primary sampling unit–interviewer experiment which was designed by the authors for implementation in the second wave of the British Household Panel Study as part of its scientific programme. It also illustrates the use of a multilevel (hierarchical) approach in which the interviewer and sample design effects are estimated simultaneously while being incorporated in a substantive model of interest.