Assumption Mapper

Extract and risk-rate hidden assumptions in a product brief or PRD. Use when asked to review a product brief for assumptions, audit a PRD for risks, find hidden assumptions, validate product plans, or run an assumption analysis. Produces a prioritised assumption map with confidence and impact scores, recommended validation methods, and critical assumption flags.

Assumption Mapper Skill

Surface and prioritize the untested assumptions embedded in any product plan before development begins.

Required Inputs

Ask the user for these if not provided:

• Product brief, PRD, or concept description (even rough notes work)
• Stage (concept / discovery / pre-build / post-launch — affects which assumptions matter most)

Process

1. Read the provided brief, PRD, or concept description
2. Extract assumptions across four categories:
   • Desirability (do users want this?)
   • Feasibility (can we build it?)
   • Viability (will it sustain the business?)
   • Usability (can users actually use it?)
3. Score each assumption:
   • Confidence (1-5): How sure are we this is true?
   • Impact (1-5): How badly does the plan fail if this assumption is wrong?
   • Priority = Impact − Confidence (higher = test first)
4. Validate completeness — Ensure at least one assumption per category. If a category is empty, re-read the brief looking specifically for that type.
5. Output a ranked list with recommended validation methods

Output Structure

Assumption Map: [Feature/Product Name]

Assumption	Category	Confidence	Impact	Priority	Validation Method
[assumption]	[type]	[1-5]	[1-5]	[score]	[method]

Critical Assumptions (Impact 4+ and Confidence 2 or below)

[Flagged items with detailed validation recommendations]

Top 3 Assumptions to Validate First

[Detailed recommendations including specific research method, estimated effort, and what the result would change]

Example (Partial)

Input: "We're building a self-serve onboarding flow to reduce time-to-value for SMB customers."

Assumption	Category	Confidence	Impact	Priority	Validation Method
SMB users can complete onboarding without human help	Usability	2	5	3	Unmoderated usability test (n=8)
Faster onboarding correlates with higher retention	Viability	3	4	1	Cohort analysis of current onboarding times vs. 90-day retention
The current onboarding is the primary reason for slow time-to-value	Desirability	2	4	2	User interviews with recent churned SMB accounts

Anti-Patterns

• Do not only surface desirability assumptions — feasibility and viability assumptions are equally likely to kill a product and are often overlooked
• Do not assign high confidence to an assumption just because it hasn't been challenged yet — absence of evidence is not evidence
• Do not recommend "user interviews" as the validation method for every assumption — some assumptions require quantitative data, competitive analysis, or technical spikes
• Do not list assumptions that cannot be tested — every assumption in the map must have a plausible validation method, or it should be flagged as unknowable and treated as a risk

Scoring Rubric (0–40)

Score any output of this skill before handing it over; 32+ is ship-quality.

Dimension	0	5	10
Category coverage	Desirability-only — the feasibility and viability assumptions most likely to kill the plan are absent	Three categories populated, but the empty one wasn't re-mined from the brief; coverage is token (one throwaway row)	All four categories populated with substantive rows, with visible digging into whichever category the brief itself neglected
Scoring discipline	Confidence/impact numbers arbitrary or missing; priority arithmetic inconsistent; no critical flags	Scores present and Priority = Impact − Confidence holds, but confidence is inflated for unchallenged assumptions and critical flags applied selectively	Scores defensible (unchallenged ≠ high confidence), arithmetic consistent including negative priorities left visible, and the CRITICAL flag applied mechanically at Impact 4+ / Confidence ≤2 — even to assumptions the team likes
Validation method fit	"User interviews" (or "do research") pasted into every row	Methods vary but several are mismatched to the assumption type, missing sample sizes, or unpriced	Each method matched to the assumption (data audit, backtest, fake door, desk check, spike…) with sample size and effort; untestable assumptions flagged unknowable and converted to owned risks, not given fake tests
Decision leverage	Top-3 list missing, or tests whose outcome would change nothing	Top 3 named with effort, but "what the result changes" is vague or the tests validate comfortable assumptions over dangerous ones	Top 3 are the highest-priority testable assumptions, each with effort, a pre-committed threshold where relevant, and a concrete decision the result would change

Quality Checks

• At least one assumption per category (Desirability, Feasibility, Viability, Usability)
• All Impact 4+ / Confidence 2− assumptions flagged as CRITICAL
• Each validation method is specific (not just "do research" — name the method and sample size)
• Priority scores are consistent (Impact − Confidence, higher = more urgent)