# Operationalizing Dyadic Urban Traffic Interaction Studies: From Theory to Practice
## 4 Results: Aspects of Traffic Interaction Study Design Warranting Trade-Offs
### Choice of Scenarios
#### 4.1.1 Categorizing Scenarios  
The location of the scenarios on road range from intersections, parking lots, shared roads (where vehicles and vulnerable road users occupy the same space with the latter having the right of way at all times), mid-block sites on roads, and merge situations. Within each of these scenarios, there can be various combinations of how a dyadic (two-agent) interaction can unfold, which is expounded in the appendices, while the final selection of the scenarios in the study from within that pool depend on the constraints explained earlier and shown in Figure 2. Based on our brainstorming sessions, we argue that it is crucial to systematically determine the grouping of traffic interactions based on the specific research question being addressed. More specifically, in a study focusing on dyadic interactions, different kinds of groupings can be derived from the research question. For instance, one potential grouping could involve scenarios where one agent possesses the right of way while the other does not, necessitating a comprehensive examination of all such scenarios. Another grouping might focus on situations where one agent proceeds straight and the other needs to turn. Additionally, a further grouping could involve both actors executing a change in direction, requiring the specification of all scenarios that fit this criterion. The choice of grouping(s) stems directly from the research question, emphasizing the need to align with the underlying inquiry, rather than advocating for any particular grouping. Our proposed strategy ensures that the interactions studied are relevant to the specific dynamics and outcomes we aim to understand, allowing for more targeted and meaningful insights into traffic behavior and safety.  
Choosing the right subset of scenarios for a traffic interaction study is a critical decision hinges critically on aligning with the research question at hand so that it balances thoroughness with practical constraints such as cost and effort. Running only one scenario might not be very informative, but attempting to cover all possible scenarios might neither be feasible nor efficient. The challenge, then, is to select a subset of scenarios that is both manageable and representative of the broader issues being investigated. Among the subset of scenarios that is chosen, it is important to articulate clearly what remains consistent across scenarios and what varies. Such clarity supports the study's internal validity by illustrating how different variables or settings influence the outcomes.  
Each scenario's inclusion in the study must be justified, explaining why these particular scenarios were chosen over others. This justification should focus on their potential to provide insights into the types of interactions being studied. Additionally, establishing a common thread or theme that runs through all scenarios helps in synthesizing findings and drawing broader conclusions. Whether it is a specific type of interaction or a shared environmental condition, this commonality ties the scenarios together and enhances the overall coherence of the research. By thoughtfully selecting and justifying these scenarios, researchers ensure that their studies are both manageable and meaningful. This structured approach not only aids in conducting focused and effective research but also strengthens the study's contribution to the broader field of traffic interaction studies, providing insightful and impactful results.  
Figure 2: Within the broader research question of studying traffic interactions, the choice of scenarios, i.e., which interaction setups to include in a study is directly dependent upon technical constraints, such as space, time, number and type of participants, as well as the degree of naturalism sought.