Accounting for nonignorable unit nonresponse and attrition in panel studies with refreshment samples

Schifeling, T., C. Cheng, Jerome Reiter, and D.C. Hillygus. "Accounting for nonignorable unit nonresponse and attrition in panel studies with refreshment samples." Journal of Survey Statistics and Methodology 3, no. 3 (2015): 265-295.