Chapter 2: Unpacking Assumptions - The Topography of Risk
Desirability, Viability, Feasibility: User Story & Impact Mapping.
Every Business is Built on Assumptions
Behind every successful product is a set of validated assumptions. Behind every failed startup is a set of assumptions that were never tested—or tested too late. This chapter gives you a framework to find, sort, and rank every assumption in your business.
The Core Insight
Your business plan isn't a set of facts—it's a collection of beliefs. The faster you can distinguish between what you know and what you assume, the faster you'll learn what actually works.
The Triad of Product Risk
Product risks fall into three categories. A successful product must pass all three tests—miss any one, and your startup fails:
Desirability
"Do they want this?"
This is where most startups fail. Key questions:
- Is the problem real and frequent?
- Is it painful enough to seek a solution?
- Do they want YOUR solution specifically?
Viability
"Should we do this?"
Even desirable products can be bad businesses. Key questions:
- Can we acquire customers profitably?
- Will they pay what we need to charge?
- Is the market large enough?
Feasibility
"Can we do this?"
Technical and operational constraints. Key questions:
- Do we have the technology?
- Is it legal and compliant?
- Can we handle operations at scale?
Where to Start?
Test Desirability first. Most founders start with Feasibility ("Can we build it?") because it's comfortable. But building something nobody wants is the #1 startup killer. Always validate demand before engineering.
Bug #1: Testing the Wrong Assumptions
Not all assumptions are created equal. Many founders waste months validating assumptions that don't actually matter.
The Bug
"We validated that we can build the technology, so we're good to go."
Technical feasibility is often the LEAST risky assumption. Proving you can build something tells you nothing about whether anyone will buy it.
The Fix
Use the Assumption Mapping Matrix.
Plot all assumptions on a 2x2 grid of Importance vs. Evidence. Focus exclusively on assumptions that are CRITICAL but UNPROVEN—the "Kill Zone."
The Assumption Mapping Workshop
Run this workshop with your team to systematically identify and prioritize what you don't know.
Workshop Setup
| Participants: | Founders + key team members (3-6 people ideal) |
| Duration: | 2-3 hours |
| Materials: | Whiteboard, sticky notes, Sharpies, or digital tool like Miro |
| Output: | Prioritized list of assumptions with experiment plans |
Step 1: Extraction (30-45 minutes)
Brainstorm every assumption underlying your business. Use these prompts to extract hidden beliefs:
Desirability Assumptions
- "Our target customer experiences [problem] regularly"
- "This problem is painful enough to pay for a solution"
- "Our solution actually solves the problem"
- "Customers will switch from their current solution"
- "Users will understand how to use our product"
Viability Assumptions
- "Customers will pay $X for this"
- "We can acquire customers for less than $Y"
- "Our target market size is at least $Z"
- "Customers will stay for at least N months"
- "We can reach customers through [channel]"
Feasibility Assumptions
- "We can build this with [technology]"
- "We can hire the talent we need"
- "This is legally permissible in our markets"
- "We can deliver within [timeframe]"
- "Partners/suppliers will work with us"
Team & Market Assumptions
- "We have the right team composition"
- "The market timing is right"
- "Competitors won't respond quickly"
- "Key stakeholders will support this"
- "Regulations won't change"
Common Extraction Mistakes
- Too abstract: "People want to save time" is too vague. Be specific: "Accountants spend 5+ hours/week on manual data entry."
- Missing implicit assumptions: "Users have smartphones" might be obvious in the US but risky in rural emerging markets.
- Skipping "obvious" ones: Your most dangerous assumptions often feel so obvious you don't question them.
Step 2: Mapping (30-45 minutes)
Plot each assumption on a 2x2 matrix:
The Assumption Mapping Matrix
X-Axis: Evidence Level
- Low Evidence (Left): Gut feeling, no data
- High Evidence (Right): Customer interviews, data, market research
Y-Axis: Business Impact
- High Impact (Top): If wrong, the business fails
- Low Impact (Bottom): If wrong, we can adapt
| Low Evidence | High Evidence | |
|---|---|---|
| High Impact | KILL ZONE Test immediately |
VALIDATED Monitor & maintain |
| Low Impact | NICE TO KNOW Test if time permits |
SAFE ZONE Ignore for now |
Step 3: Prioritize the Kill Zone (30 minutes)
For assumptions in the Kill Zone (high impact, low evidence), prioritize using this formula:
Prioritization Formula
Priority Score = Impact × Uncertainty × Speed of Testing
- Impact (1-10): How catastrophic if wrong?
- Uncertainty (1-10): How little do we know?
- Speed (1-10): How quickly can we test it? (higher = faster)
Test the highest-scoring assumptions first.
Step 4: Design Experiments (45 minutes)
For each priority assumption, define an experiment using this template:
Experiment Design Template
| Assumption: | [What we believe to be true] |
| Experiment Type: | [Interview / Landing Page / Fake Door / Concierge] |
| Sample Size: | [How many people/interactions] |
| Success Metric: | [What we'll measure] |
| Pass Threshold: | [The number that means "validated"] |
| Deadline: | [When we'll have results] |
Bug #2: Building Features Without Outcomes
Many teams build features because they seem like good ideas—without connecting them to measurable business outcomes.
The Bug
"Let's add dark mode—users will love it."
Features that don't connect to business outcomes create bloat, delay launch, and waste engineering time. "Users might like it" isn't a strategy.
The Fix
Use Impact Mapping.
Every feature must connect to a behavior change that helps a business goal. No link = no build.
Impact Mapping: Why Before What
Impact Mapping connects what you build to business goals in four steps:
The Impact Map Structure
| Level | Question | Example |
|---|---|---|
| Goal | Why are we doing this? | Increase revenue by 30% |
| Actors | Who can help or hinder? | Event organizers, attendees, sponsors |
| Impacts | How should their behavior change? | Organizers create events more frequently |
| Deliverables | What can we build to cause this? | Mobile admin app, event templates |
The Feature Justification Test
Before adding any feature to your backlog, answer: "What behavioral change will this cause, and how does that impact our goal?" If you can't answer clearly, the feature doesn't belong in your MVP.
User Story Mapping: End-to-End Completeness
Impact Mapping asks why. User Story Mapping asks what—making sure your MVP covers the full journey, not just one piece.
User Story Map Structure
Arrange stories in a grid that represents the user's journey:
| Discover | Sign Up | Onboard | Core Action | Share |
|---|---|---|---|---|
| View landing page | Create account | Complete profile | Create first item | Invite teammate |
| Watch demo video | OAuth login | Tutorial flow | Edit item | Share via link |
| Read testimonials | SSO integration | Import data | Bulk actions | Export report |
The MVP Line: Draw a horizontal line. Everything above is your MVP—the minimum stories needed to complete the full journey. Green row = MVP. Yellow row = Next release.
Common Story Mapping Mistake
Building 100% of "Sign Up" but 0% of "Core Action." A user can create an account beautifully—but then has nothing to do. Story Mapping makes these gaps visible before you build.
Your Assumption Unpacking Checklist
Before Moving to Build
| Desirability validated: You have evidence that customers want this specific solution | |
| Viability tested: You've validated willingness to pay at your target price | |
| Kill Zone cleared: All high-impact, low-evidence assumptions have experiments | |
| Impact map created: Every feature links to a behavioral change and business goal | |
| Story map drawn: Your MVP is end-to-end complete, not deep in one area |
Key Takeaways
Remember These Truths
- Test Desirability first. Most startups fail because no one wants the product—not because they couldn't build it.
- Find the Kill Zone. Focus exclusively on assumptions that are high-impact and low-evidence.
- Link features to outcomes. Use Impact Mapping to justify every feature with a behavioral change and business goal.
- Ensure end-to-end completeness. Use Story Mapping to avoid building deep in one area while leaving critical gaps.
- Run the workshop. Assumption mapping isn't a solo activity—diverse perspectives catch hidden assumptions.
Now that you can systematically unpack and prioritize assumptions, let's explore the specific techniques for validating them without writing code.
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RAT vs MVP Philosophy
- 1. Ries, E. (2011). The Lean Startup. Crown Business.
- 2. "Why RAT (Riskiest Assumption Test) beats MVP every time." LinkedIn
- 3. "Pretotyping: The Art of Innovation." Pretotyping.org
- 6. "Continuous Discovery: Product Trio." Product Talk
- 7. "MVP Fidelity Spectrum Guide." SVPG
Minimum Lovable Product
- 8. Olsen, D. (2015). The Lean Product Playbook. Wiley.
- 9. "From MVP to MLP: Why 'Viable' Is No Longer Enough." First Round Review
- 10. "Minimum Lovable Product framework." Amplitude Blog
Hypothesis-Driven Development
- 11. Gothelf, J. & Seiden, J. (2021). Lean UX. O'Reilly Media.
- 12. "Hypothesis-Driven Development in Practice." ThoughtWorks Insights
- 13. "Experiment Tracking Best Practices." Optimizely
- 14. "Build-Measure-Learn: The Scientific Method for Startups." Harvard Business Review
Assumption Mapping
- 15. Bland, D. & Osterwalder, A. (2019). Testing Business Ideas. Wiley.
- 16. "Risk vs. Knowledge Matrix." Miro Templates
- 17. "Identifying Riskiest Assumptions." Intercom Blog
User Story & Impact Mapping
- 20. Patton, J. (2014). User Story Mapping. O'Reilly Media.
- 21. Adzic, G. (2012). Impact Mapping. Provoking Thoughts.
- 22. "Jobs-to-Be-Done Story Framework." JTBD.info
- 23. "The INVEST Criteria for User Stories." Agile Alliance
- 24. "North Star Metric Framework." Amplitude
- 25. "Opportunity Solution Trees." Product Talk
- 26. Torres, T. (2021). Continuous Discovery Habits. Product Talk LLC.
Pretotyping Techniques
- 27. Savoia, A. (2019). The Right It. HarperOne.
- 28. "Fake Door Testing Guide." UserTesting
- 29. "Wizard of Oz Testing Method." Nielsen Norman Group
- 30. "Concierge MVP Explained." Grasshopper
Prioritization Frameworks
- 31. "ICE Scoring Model." ProductPlan
- 32. "RICE Prioritization Framework." Intercom
- 33. "Kano Model for Feature Analysis." Folding Burritos
- 34. "MoSCoW Method Guide." ProductPlan
Build vs Buy & No-Code
- 35. "No-Code MVP Tools Landscape." Makerpad
- 37. "Technical Debt in Early Startups." a16z
- 38. "Prototype Fidelity Selection." Interaction Design Foundation
- 39. "API-First Development Strategy." Swagger
- 40. "Rapid Prototyping with Bubble & Webflow." Bubble Blog
Metrics & Analytics
- 41. Croll, A. & Yoskovitz, B. (2013). Lean Analytics. O'Reilly.
- 42. "One Metric That Matters (OMTM)." Lean Analytics
- 43. McClure, D. "Pirate Metrics (AARRR)." 500 Startups
- 44. "Vanity Metrics vs. Actionable Metrics." Mixpanel
- 45. "Cohort Analysis Deep Dive." Amplitude
- 46. "A/B Testing Statistical Significance." Optimizely
- 47. "Product Analytics Instrumentation." Segment Academy
- 48. "Activation Metrics Framework." Reforge
- 49. "Leading vs Lagging Indicators." Productboard
- 50. "Retention Curve Analysis." Sequoia Capital
- 51. "Feature Adoption Tracking." Pendo
- 52. "Experimentation Velocity Metrics." ExP Platform
Launch Operations & Analysis
- 53. "Soft Launch Strategy." Mind the Product
- 54. "Feature Flag Best Practices." LaunchDarkly
- 55. "Beta Testing Program Design." BetaList
- 56. "Customer Feedback Loop Systems." Canny
- 57. "Rollback Strategy Planning." Atlassian
- 58. "Why Startups Fail: Post-Mortems." CB Insights
- 59. "Pivot vs Persevere Decisions." Steve Blank
- 60. "Learning from Failed Experiments." HBR Innovation
This playbook synthesizes methodologies from Lean Startup, Design Thinking, Jobs-to-Be-Done, Pretotyping, and modern product management practices. References are provided for deeper exploration of each topic.