Beyond Workflow Structure: A Formative Study of a Web Tool for Systems-Theoretic Safety Analysis

Preprint submitted to the International Journal of Human–Computer Interaction; not peer reviewed. Data and materials: https://doi.org/10.5281/zenodo.23197005 Software increasingly carries complex analytical methods, promising consistency and wider access. I report the design and formative evaluation of a web tool that encodes System-Theoretic Process Analysis (STPA) and Causal Analysis based on System Theory (CAST), together with structured prompts from the Sagacity Analysis Framework Extension (SAFE). Eleven participants, nine reporting 0–2 years of hazard-analysis experience, undertook analyses remotely and returned post-task feedback. Participants valued procedural organization, automatic diagramming, and some conceptual guidance, while reporting difficulties with scenario development, mitigation, editing, and workspace organization. A descriptive audit of the exported records identified 40 scenarios: 25 component-linked and 15 linked to unsafe control actions. Fourteen lacked narrative descriptions, and explanatory text was stored differently across pathways. One human-behavior entry carried physical-actuator labels; other records showed missing or semantically inconsistent links. These observations concern recorded representations, not demonstrated changes in participants' reasoning. Participants who expanded the cases encountered additional workspace difficulties, but task choice and experience were confounded. The Scaffolded Analytical Interface Design (SAID) propositions distinguish procedural support, representational fidelity, and analytical adequacy, and motivate comparative tests of contextual guidance, reviewable classifications, and scalable workspaces. The study did not measure learning, independent competence, or causal effects of interface features.