Calderwood, Lisa, Ian Plewis, Sosthenes Ketende, and Tarek Mostafa. 2016. “Evaluating the Immediate and Longer Term Impact of a Refusal Conversion Strategy in a Large Scale Longitudinal Study”. Survey Research Methods 10 (3):225-36. https://doi.org/10.18148/srm/2016.v10i3.6275.