Operational Definitions of Time for Longitudinal Data Analysis: Illustration in the Field of Spatial Mobilities
Temporality of human and social phenomena raises theoretical complex issues and specific technical challenges, including analyzing and visualizing of temporal information. This paper proposes an operational typology of three kinds of time: schedule-time, process-time and succession-time. Then it illustrates the usefulness of this typology through three case studies dealing with mobility (residential trajectories, programs of activities and daily trips, routes of freight delivery). These examples are analyzed using longitudinal data and several modes of graphical representation (distribution plot, sequence frequency plot, slide plot). Our approach is willing to enrich and clarify the understanding of time as an attribute into a statistical information system. This approach is inductive and pragmatic: we started with specific thematic and technical issues regarding the analysis and the graphical representation of longitudinal data to move towards theoretical specifications of time. In short, we tried to model an appropriate time to our research objects. This research approach is rendered in reverse in the article: from the theoretical thinking about time to the field of spatial mobility.