Assessing the mode dependency of sample selectivity across the survey response process

Survey researchers currently act on three beliefs when combining survey modes in mixed-mode designs. First, modes elicit distinct patterns of survey response behaviour and nonresponse bias. Second, these selection differences are caused by differences in the response process of differential coverage, contact and cooperation. Third, mode-dependent response patterns might be exploitable by sequential mixed-mode designs ideally yielding samples less biased by selection and hence more ‘representative’. These assumptions are assessed using a factorial design, in which the Dutch Crime Victimisation Survey was administered either in CAPI, CATI, mail, or web.