A good mix? Mixed mode data collection and cross-national surveys

Can cross-national surveys benefit from mixed mode data collection? This article provides a classification of the different ways in which modes of data collection may be mixed within a cross-national survey, and investigates the methodological consequences of such designs. Mixed mode designs have the potential to lower survey costs relative to single-mode face-to-face surveys, while maintaining higher response rates than cheaper modes alone could. Yet since responses to survey questions are not always independent of the survey mode, mixed mode designs endanger cross-national measurement equivalence (as well as, in the case of time series surveys, diachronic equivalence), so that cross-national comparisons (and analyses of change over time) lose internal validity. These problems can be mitigated by careful questionnaire and survey design, but won’t be entirely overcome in many cases. The use of mixed mode designs in cross-national surveys therefore needs to be accompanied by methodological research to establish the likely consequences for measurement