Fig. 4From: Mixing modes in a population-based interview survey: comparison of a sequential and a concurrent mixed-mode design for public health researchTimeline of valid questionnaires obtained by mixed-mode design and number of contacts. SAQ-Paper = self-administered paper questionnaire; SAQ-Web = self-administered web questionnaire; CATI = computer-assisted telephone interview; percentages according to mixed-mode-designsBack to article page