We consider the effect of a wave of mixed-mode data collection (telephone and face-to-face), in an otherwise face-to-face survey, 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. One protocol involves making extended efforts to interview each household member by telephone before switching to face-to-face, while 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. With both protocols response rate at the mixed-mode wave is lower than with face-to-face single mode data collection, but with the protocol involving extended efforts this response differential is eroded over the following two waves.
(2012) Mode-switch protocols: how a seemingly small design difference can affect attrition rates and attrition bias, Understanding Society Working Paper 2012-07, Colchester: University of Essex