Toward a General Theory of Diary Panels
This article represents an integration of findings reported in seven articles on diary panels that the authors have published, based on the AT&T database. There are four major issues involved with diary panels, to wit: respondent noncooperation involving item nonresponse and attrition, bias leading to estimation errors, mathematical artifacts involving regression toward the mean, and the conditioning effect of being observed. An integrated conceptual framework for diaries is advanced, consisting of five independent variables (questionnaire design, length of participation, level of aggregation, duration of usage, and defining usage rate with length used), four mediating variables (degree of difficulty, participation fatigue, natural mortality, and level of involvement), and six dependent variables (item nonresponse, attrition, accuracy, regression toward the mean, the conditioning effect, and estimation regression). This attempt at a general theory of diary panels is admittedly incomplete, but is meant to serve as a useful conceptual framework for further research on longitudinal studies involving record keeping and reporting.