Question 1

What is assumption mapping?

Accepted Answer

A team exercise that makes the beliefs behind a product idea explicit, then prioritizes them on a matrix by importance and evidence, so the riskiest assumptions can be tested before building.

Question 2

Who created assumption mapping?

Accepted Answer

David J. Bland developed and popularized it, notably in his 2020 book "Testing Business Ideas," co-authored with Alexander Osterwalder. He credits early exposure to the idea to work with Jeff Gothelf and Josh Seiden.

Question 3

What is the central question in assumption mapping?

Accepted Answer

What are all the things that need to be true for this idea to work? Every assumption that answer surfaces becomes a candidate for testing.

Question 4

What are the main types of risk it covers?

Accepted Answer

Desirability (do they want it), feasibility (can we build it), and viability (should we do it), with many teams adding adaptability (can it survive change).

Question 5

What are the two axes of the assumption matrix?

Accepted Answer

Importance (how much rides on the assumption) and evidence, or known versus unknown (how much proof you currently have).

Question 6

Which quadrant matters most?

Accepted Answer

The top-right: assumptions that are both important and unknown. These critical, unproven beliefs are where an idea is most likely to fail, so they are tested first.

Question 7

Why do teams often test the wrong assumptions?

Accepted Answer

Because they gravitate toward comfortable or feasible questions, especially "can we build it," while neglecting whether anyone wants it or whether it makes business sense.

Question 8

Is the map itself the goal?

Accepted Answer

No. Bland emphasizes that the shared conversation during mapping is more valuable than the finished map, since it surfaces the team’s real disagreements and blind spots.

Question 9

What format should assumptions be written in?

Accepted Answer

Short, specific, testable statements, often using the "We believe that..." format, which shifts the team toward the mindset that they might be wrong.

Question 10

What happens after mapping?

Accepted Answer

The team designs cheap, fast experiments for the important, unproven assumptions and runs them before committing to building, using the results to decide whether to proceed.

What Is Assumption Mapping?

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