Text-aided Group Decision-making Process Observation Method (x-GDP): a novel methodology for observing the joint decision-making process of travel choices

Joint travel decisions, particularly related to social activities remain poorly explained in traditional behavioral models. A key reason for this is the lack of empirical data, and the difficulties associated with collecting such data in the first place. To address this problem, we propose Text-aided Group Decision-making Process Observation Method (x-GDP), a novel survey methodology to collect data on joint activities from all members of a given clique. More specifically, on a Zoom-moderated experiment, participant cliques are asked to coordinate an activity (or set of activities) using a group chat interface. The experiment requires not only the coordination but the execution of the planned activity, thus guaranteeing a real discussion that takes into consideration the preferences and constraints of clique members. Through this method we are able to observe not only the outcome of the choice process, but also the decision-making process itself in a quasi-naturalistic manner, including the alternatives that compose the choice set, individual and clique characteristics that might affect the choice process, as well as the discussion behind the choice via texts. In this paper we introduce the results of an x-GDP survey implementation focusing on joint eating-out activities in the Greater Tokyo Area. Preliminary data analysis clearly illustrates the heterogeneity of the choice processes among groups and how members’ spatiotemporal constraints, individual and relational characteristics, as well as the bargaining process affect choice outcomes. Given the unique characteristics of the collected data, we discuss how x-GDP can be used to (i) identify and categorize group decision-making patterns, (ii) model group decisions explicitly considering the decision-making process, (iii) estimate joint accessibility measures and (iv) analyze choice set generation processes.