Give them a call! About the importance of call-back strategies in panel surveys

Building on an experiment introduced in the French probabilistic web panel Longitudinal Internet Studies for Social Sciences (ELIPSS), this paper provides estimates of the effect of a callback strategy of nonrespondents to specific waves to increase overall participation. Comparing groups in accordance with their previous pattern of participation and a treatment deciding whether a telephone callback was implemented in case of nonresponse, we test the conditionality of the callback effect on previous participation patterns. The panellists’ probability of response decreased proportionally to the number of studies missed out, while the motivating effect of telephone callbacks seemed independent from this factor. Hence, this paper lends credence to the assumption that the effectiveness of callback strategies is quite stable irrespective of the panellists’ level of commitment.