# Revisiting Problem-Solution Co-Evolution in the Context of Team Conceptual Design Activity
## 4 Discussion
### Revisiting Co-Evolution  
The intention of the presented research was not to question the validity of existing prescriptive and descriptive design research. Instead, the goal was to complement the literature with insights obtained within the team conceptual design activity context. According to the conducted hypotheses tests, there exist deviations from the assumptions based on the well-established design process models:  
* Analysis-intensive fragments of team design activities are likely to exhibit higher proportions of state transitions related to solution space exploration, whereas the synthesis-intensive fragments associate to higher proportions of transitions related to the exploration of the problem space. * Neither the analysis-synthesis-evaluation nor the synthesis-analysis-evaluation sequences dominate on a fine-grain process level of team design activity. * Co-evolution has a significantly higher effect on synthesising new problem entities than it does on generating new solution entities. These three findings can be further elaborated and discussed by laying out an additional perspective of the experimental sessions, that is the temporal analysis of the number of problem and solution entities being generated when designing in teams. Figure 8 shows the change in the cumulative number of both problem and solution entities generated by the four teams throughout the deciles of ideation and concept review experimental sessions. Such a breakdown of design activity protocols into 10 parts is often used to depict the process dynamics during the activity [46; 90]. Namely, the splitting of sessions into 10 parts provides an even more detailed description of the dynamics in which new design entities are generated. The cumulative number of design entities includes only the entities generated during the two team activities, although it can be assumed that the participants generated additional entities when working individually. Nevertheless, the here-presented discussion focuses solely on the team activity aspect. The visualised change in the number of design entities reveals interesting trends in how teams generate new problem and solution entities. During most of the ideation, which has been characterised as a synthesis-intensive activity [43], the number of both the new problem and solution entities increases in a constant pace, with a small decrease in the number of new problems towards the end of the activity. Moreover, the number of new problems practically stagnates throughout concept review. In contrast, the pace of generating new solutions extends also to concept review, with a small decrease towards the end of the activity for three of the teams. These trends are in line with studies that attempted to quantify the focus on problem versus solution space exploration. For example, the studies that measured the problem-solution indicator for team designing [46; 90; 91] have shown that the proportion of problem-related issues tends to decrease with the progress of the conceptual design activity. A study focused on the phenomena of identifying requirements has shown similar results: The rate at which the requirements are identified and evolve decreases with the progress of the design process [92; 93]. Of course, the exact number of new problem entities may vary depending on the methods or tools used (e.g., in case of different tools and techniques for requirements' formulation [94; 95]); however, the described trends tend to persist. The conceptual design process thus moves from divergent to convergent activity [85], that is from the problem-focused task clarification and idea generation towards the solution-focused design reviews [43; 96]. In addition, a study of freshman and senior students' conceptual design process [97] revealed that the focus on problem scoping, that is problem definition and information gathering, has been most persistent from the beginning up until the end of the first half of the conceptual design stage.