Visualising Complexity in Psychological Practice: The Ishikawa Diagram as a Method for Formulation, Supervision, Safety Planning, and Service Design

The Ishikawa (fishbone) diagram, long established in quality-improvement and systems engineering, offers a visual method for mapping interdependent factors in complex human problems. This paper positions the Ishikawa diagram as a reflective and collaborative framework for clinical psychology, bridging systemic and constructivist perspectives on case formulation, supervision, and team-based planning. Contrasted with directed acyclic graphs (DAGs), which formalise causal hypotheses for empirical testing, the Ishikawa approach externalises multifactorial influences to support meaning-making, shared understanding, and decision transparency. Illustrative applications in case formulation, supervision, safety planning, and risk assessment demonstrate its capacity to translate systems thinking into everyday clinical and service-development practice. This framework serves as a foundation for a proposed research agenda to evaluate feasibility and training implications, while providing a ready-to-use bridge between systems engineering and psychological formulation models. Keywords: Ishikawa diagram; systems thinking; psychological formulation; clinical supervision; reflective practice; collaborative planning; service design