lean-ux

What this skill does

# Lean UX Framework

A practice-driven approach to user experience design that replaces heavy deliverables with rapid experimentation, cross-functional collaboration, and continuous learning. Based on a fundamental truth: teams that obsess over pixel-perfect specs before testing with real users waste months building the wrong thing. Lean UX shifts the question from "What should we design?" to "What do we need to learn?"

## Core Principle

**Outcomes over outputs.** The value of a design is not measured by the fidelity of the deliverable but by the change in user behavior it produces.

**The foundation:** Traditional UX waterfalls requirements into wireframes, wireframes into mockups, mockups into specs, and specs into code. At every handoff, context is lost and assumptions go untested. Lean UX eliminates waste by compressing the distance between idea and evidence. Instead of debating opinions in conference rooms, teams declare assumptions, form hypotheses, run the smallest possible experiment, and let real user behavior settle the argument. Shared understanding replaces documentation. Learning velocity replaces pixel perfection.

## Scoring

**Goal: 10/10.** When reviewing or creating UX processes, design plans, or team workflows, rate them 0-10 based on adherence to Lean UX principles. A 10/10 means full alignment with hypothesis-driven design, minimal deliverables, collaborative practices, and outcome-focused metrics; lower scores indicate heavy-deliverable thinking or untested assumptions. Always provide the current score and specific improvements needed to reach 10/10.

### 1. Declaring Assumptions

**Core concept:** Every design starts with assumptions. Lean UX makes those assumptions explicit so they can be prioritized and tested, rather than baked invisibly into specifications.

**Why it works:** When assumptions remain unspoken, teams build on shaky ground and discover problems only after launch. By surfacing assumptions early, the team can focus energy on the riskiest ones first, reducing the cost of being wrong.

**Key insights:**
- Business assumptions define what must be true for the business to succeed (revenue model, market size, willingness to pay)
- User assumptions define who the users are, what they need, and what behaviors they exhibit
- Assumption prioritization is based on two axes: risk (how damaging if wrong) and uncertainty (how little we know)
- High-risk, high-uncertainty assumptions are tested first
- The team writes assumptions collaboratively, not in isolation

**Product applications:**

| Context | Application | Example |
|---------|-------------|---------|
| **New feature kick-off** | Assumption mapping workshop | "We assume users want to share reports with teammates" |
| **Redesign initiative** | Identify what you believe about current users | "We assume users leave because the dashboard is confusing" |
| **Roadmap planning** | Rank features by assumption risk | Prioritize features whose success depends on untested beliefs |
| **Stakeholder alignment** | Expose hidden assumptions across roles | PM assumes pricing works; engineer assumes scale works; designer assumes flow works |

**Ethical boundary:** Assumptions should be honest assessments, not post-hoc justifications for decisions already made. If leadership has already committed to a direction, acknowledge that constraint rather than pretending the assumption is open to falsification.

See: [references/hypothesis-canvas.md](references/hypothesis-canvas.md)

### 2. Hypothesis Statements

**Core concept:** A hypothesis translates an assumption into a testable prediction. The Lean UX hypothesis format links a proposed change to a measurable outcome for a specific user segment.

**Why it works:** Hypotheses force precision. Instead of "make onboarding better," the team commits to a specific prediction that can be proven or disproven. This prevents scope creep, sharpens success criteria, and makes the learn step unambiguous.

**Key insights:**
- Standard format: "We believe [outcome] will happen if [persona] achieves [action] with [feature]"
- Every hypothesis should specify the persona, action, outcome, and measurable signal
- Sub-hypotheses break a large bet into smaller, independently testable parts
- Hypotheses are not goals; they are predictions that could be wrong
- The team must agree on what "validated" and "invalidated" look like before running an experiment

**Product applications:**

| Context | Application | Example |
|---------|-------------|---------|
| **Feature design** | Write hypothesis before wireframing | "We believe trial-to-paid conversion will increase by 10% if new users complete a guided setup wizard" |
| **A/B tests** | Formalize test rationale | "We believe click-through will rise 15% if we move the CTA above the fold" |
| **Sprint planning** | Attach hypothesis to each user story | Story: "As a user I can filter by date." Hypothesis: "We believe task completion time drops 30%" |
| **Retrospectives** | Review validated vs. invalidated hypotheses | "3 of 5 hypotheses validated this quarter; 2 pivoted" |

**Ethical boundary:** Never cherry-pick metrics after the fact to declare a hypothesis validated. Pre-commit to success criteria.

See: [references/hypothesis-canvas.md](references/hypothesis-canvas.md)

### 3. MVPs and Experiments

**Core concept:** An MVP in Lean UX is the smallest design artifact that can test a hypothesis with real users. It is not a product launch; it is a learning tool.

**Why it works:** Heavy deliverables delay learning. A paper prototype tested with five users in a hallway can invalidate a hypothesis that would otherwise consume a full sprint of engineering. By matching experiment fidelity to the risk of the assumption, teams learn faster and waste less.

**Key insights:**
- Experiment types range from low fidelity (paper prototypes, concierge tests) to high fidelity (coded A/B tests, Wizard of Oz)
- Choose the lowest-fidelity experiment that can answer the question
- A good experiment has a clear hypothesis, defined audience, measurable signal, and time box
- "Proto-personas" can stand in for full research when speed matters, but must be validated later
- The goal is to learn, not to ship

**Product applications:**

| Context | Application | Example |
|---------|-------------|---------|
| **Early concept validation** | Paper prototype or clickable mockup | Sketch 3 concepts, test with 5 users same day |
| **Demand validation** | Landing page smoke test | "Sign up for early access" measures real interest |
| **Usability validation** | Clickable prototype test | Figma prototype tested with 5-8 users |
| **Technical feasibility** | Wizard of Oz | Manual backend, automated frontend to test experience |
| **Pricing validation** | Painted door test | Show pricing page, measure click-through before building billing |

**Ethical boundary:** Smoke tests and fake door tests must not mislead users into believing a product exists when it does not. Always disclose the test status and offer a way to opt out.

See: [references/experiment-patterns.md](references/experiment-patterns.md)

### 4. Collaborative Design

**Core concept:** Design is a team sport. Lean UX replaces the solitary designer-then-handoff model with cross-functional design sessions where developers, product managers, and designers sketch solutions together.

**Why it works:** When the whole team participates in design, shared understanding replaces documentation. Developers who helped sketch the solution do not need a 40-page spec to build it. Diverse perspectives generate more creative solutions. Handoff waste drops dramatically.

**Key insights:**
- Design Studio method: diverge (individual sketching), present, critique, converge (refined sketch), iterate
- Shared understanding is the currency of Lean UX; it replaces heavy documentation
- Style guides and pattern libraries are living documents, not static PDFs
- The goal is not consensus but informed commitme