Alternative Sequential Mixed-Mode Designs: Effects on Attrition Rates, Attrition Bias, and Costs

This article considers the effect that a wave of mixed-mode data collection (telephone and face-to-face), in an otherwise face-to-face survey, can have on panel attrition and the extent to which this effect is dependent on the nature of the mode-switch protocol. Findings are reported from an experiment carried out at wave 2 of the UK Household Longitudinal Study Innovation Panel, a survey in which the objective is to interview each adult member of the household. One protocol involves making intensive efforts to interview each household member by telephone before switching to face-to-face, and the other involves switching a household to face-to-face as soon as it is apparent that an interviewer visit will be needed for at least one household member. I assess effects on response at waves 2, 3, and 4. With both protocols response rate is lower at wave 2 than with face-to-face single-mode data collection, but with the protocol involving intensive efforts, this response differential is eroded by wave 4, whereas with the other protocol the difference remains. This difference in effect may be caused by intra-household communications.