Attrition

Unit nonresponse is a problem for any type of survey; however, unit nonresponse in panel studies can be a more severe problem than in cross-sectional studies. [Page 43]Like cross-sectional studies, panel studies are subject to nonresponse at the initial wave. In addition, attrition—which is unit nonresponse after the initial wave of data collection—can occur at each subsequent wave.

A framework for understanding attrition in panel studies divides the participation process into three conditional steps: (1) location, (2) contact given location, and (3) cooperation given contact; this process cycle is repeated at each wave. Attrition thus occurs because of a failure to relocate or recontact an eligible sample unit after the initial wave of data collection, and because of noncooperation (i.e. a refusal to participate again in ...