Workload, Response Rate, and Data Yield: Experiments with Long-Distance Diaries

Workload, response rate, data yield, and data quality of travel diaries are interacting variables. It has long been suspected that it is impossible to maximize all variables at the same time. Still, empirical work trying to improve understanding of the trade-offs among them has been rare. Results are reported of experiments with long-distance diaries, which aim to clarify some of the possible relationships. The object of experimentation is surveys of long-distance travel behavior, which are currently of particular interest in Europe and elsewhere. The development of the tourism industry, deregulation of the long-distance modes, and infrastructure concerns require improved data about long-distance travel, both in improved inventories and in improved behavioral understanding. The experiments undertaken varied the workload of the respondents by varying the number of items to be reported about any long-distance journey, the duration of the survey period, and the temporal orientation of the survey. The results indicate that the response rate and the data yield, that is, the number of reported journeys and stages, change systematically with changes in the experimental variables (reduced response rates for prospective surveys, reduced number of reported journeys, and stages for retrospective surveys). Detailed results for these trade-offs are given. The trade-offs force the designer of such surveys to choose carefully and to invest time and effort in correcting for the potential biases resulting from this systematic behavior.