── ── Mental model
Design Thinking
Design thinking — formalized by Tim Brown at IDEO and Stanford's d.school, grounded in Simon (1969) and Rittel's "wicked problems" — replaces assumption-driven decisions with evidence from observed human behavior. Its three-lens test: every viable innovation must sit at the intersection of desirability, feasibility, and viability. Most product failures are desirability failures; teams built something technically sound that people did…
How it works
Run the Design Sprint through five stages (divergent → convergent, checkable output at each).
1. Empathize: Observe real users in context (30–60 min interviews; contextual observation; extreme users). Stop-rule: survey responses alone = stage incomplete. 2. Define: Sort observations by theme → find say/do contradictions → write insight statement → reframe as "How Might We" (HMW). Deliverable: 3–5 ranked HMWs. Stop-rule: HMW contains a solution → return to synthesis. 3. Ideate: Silent writing → share → cluster → dot-vote → select 3–5 for prototyping. Stop-rule: <20 concepts before convergence = ideation was skipped. 4. Prototype: Minimum artifact to test the core assumption; one explicit learning question per prototype; 4-hour ceiling. Stop-rule: polishing without a new assumption = stop. 5. Test: Define 3 hypotheses → observe, do not defend → debrief immediately → iterate within 24 h. Run 2–3 full cycles. Stop-rule: "users loved it" = insufficient testing.
When to use it
- user asks 'why isn't anyone using our product?', 'how do we understand what customers really want?', 'we know the tech works but the market isn't responding', team is stuck on a single solution and needs divergent ideas, or someone discusses user research / personas / prototyping / iterative design
When not to use it
When the decision is routine and reversible, applying a formal method costs more than it returns.
Worked example
GE Healthcare — Pediatric MRI Redesign (2007)
In 2007, GE Healthcare conducted a study across major US pediatric hospitals and found that more than 40% of children aged 3–10 required sedation for MRI scans because they could not remain still. Sedation carried medical risk and added $7,000–$12,000 per scan in anesthesiologist costs.
Install this skill (free, MIT)
npx skills add deciqAI/knowledge-skills