The impact of contact effort on mode-specific selection and measurement bias

In 2011, a large-scale mixed-mode experiment was linked to the Crime Victimisation Survey (CVS). This experiment consisted of a randomized allocation of sample persons to the four contemporary survey modes Web, mail, telephone and face-to-face, and a follow-up using only interviewer modes. The aim of the experiment was to disentangle mode-specific selection- and measurement bias. In a previous paper (Schouten et al 2013), mode-specific selection and measurement biases were reported for a large number of key variables from the CVS and the Labour Force Survey. This paper is a follow-up to that study and investigates the size of the selection and measurement biases as a function of contact effort, where contact effort refers to the number of telephone calls, the number of face-to-face visits and the number of reminders in Web and mail. In the analyses, face-to-face response based on a maximum of six visits, the default face-to-face strategy at Statistics Netherlands, is used as the benchmark. The analyses show that contact effort has little impact on the size of measurement bias and a modest impact on the size of selection bias. From the results, it is therefore concluded that contact effort is not a strong common cause of nonresponse and measurement error