Assumption Mapping surfaces testable hypotheses behind an idea and prioritizes them by importance and existing evidence. This guide follows the 2×2 variant described by David J. Bland and Strategyzer.

1. 1

   Decision

   Frame the decision and idea

   

   Goal

   The team understands what is at stake if assumptions are wrong.

   Inputs for this step

   • Decision or offer
   • Target user and success criterion

   Actions

   • Name the idea or decision clearly.
   • Discuss success and the consequences of being wrong.
   • Consider desirability, viability, feasibility and other relevant risk areas.

   Output

   Idea frame and consequences

   Decision · success · consequence

   Quality check

   Can the team name what could cause the idea to fail?

   Pitfall

   The team lists solutions without a shared decision or goal. Frame the idea and intended result first; then surface its underlying beliefs.

   Timing: About 10 minutes.

2. 2

   Assumptions

   Phrase assumptions as hypotheses

   

   Goal

   Assumptions are observable and distinct.

   Inputs for this step

   • Idea and intended result
   • Customer, business and delivery knowledge

   Actions

   • Surface assumptions about customer value, viability, feasibility or adoption.
   • Split vague beliefs into precise, testable hypotheses.
   • Link each statement to existing evidence or mark it as unsupported.

   Output

   List of testable hypotheses

   Statement · risk area · possible evidence

   Quality check

   Is each card one distinct and testable statement?

   Pitfall

   An aspiration or goal is mistaken for a hypothesis. State what is believed to be true and what observation could support it.

   Timing: About 20 minutes.

3. 3

   Map risk

   Map importance and evidence together

   

   Goal

   Critical assumptions with weak evidence become visible learning priorities.

   Inputs for this step

   • Hypothesis list
   • Available evidence and sources

   Actions

   • Discuss whether the idea fails if an assumption is false.
   • Examine the strength and recency of evidence, not just subjective confidence.
   • Place assumptions qualitatively on the 2×2 map and flag disagreements.

   Output

   Assumption map with rationale

   Importance · existing evidence · disagreement

   Quality check

   Are top priorities both important and weakly evidenced? Are placements based on sources rather than the loudest opinion?

   Pitfall

   The group assigns falsely precise probabilities or averages. Use relative positions as a conversation aid; record evidence and disagreement openly.

   Timing: About 20 minutes.

4. 4

   Plan tests

   Turn the riskiest assumption into a test plan

   

   Goal

   The workshop ends with a prioritized plan to examine one critical uncertainty.

   Inputs for this step

   • Important hypotheses with weak evidence
   • Access to customers, data or technical evaluation

   Actions

   • Choose a suitable test and evidence source for an important assumption with little evidence.
   • Record the expected signal and possible decision for positive or negative results in advance.
   • Assign an owner, date and review point for execution after the workshop.

   Output

   Prioritized test plan for critical assumptions

   Hypothesis · test · signal · decision · owner

   Quality check

   Does the planned test examine risk rather than generic concept interest? Is it clear how the later decision depends on the result?

   Pitfall

   A test plan is presented as if evidence had already been collected. Run the test after the workshop and update the map when evidence arrives.

   Timing: About 15 minutes for test selection and planning; execution and evidence review follow separately.