Riskiest Assumption Test Kit
Every bet rests on beliefs — this kit finds the one yours most depends on, and turns it into the smallest test that could change your plan. An assumption inventory, the importance × evidence grid, and a fillable test card. Print it, or save it as a PDF.
Tip: in the print dialog, choose Save as PDF and turn on background graphics for the tidiest result.
Test-card kit
outcomify.com
Riskiest Assumption Test
One bet · 30–45 minutes · solo or with your trio. Find the belief your bet most depends on — and test it before you build.
How it works
Six steps. The discipline is picking the riskiest belief — not the easiest one to check.
- 1List the beliefs your bet depends on — customers want it, they can use it, you can build it, it works for the business.
- 2Rate each one: how important is it (does the bet collapse if it’s wrong?) and how much evidence you already have.
- 3Map them on the importance × evidence grid. High importance + low evidence is your leap-of-faith corner.
- 4Pick the single riskiest assumption — not the easiest to test, the one that would change your plan the most.
- 5Design the smallest test that gives a clear signal, and write the success criterion before you run it.
- 6Run it and decide: validated → next assumption; invalidated → change the plan; inconclusive → sharpen the test.
The bet
Name what you’re about to spend real time on. If the bet is fuzzy, the assumptions will be too.
List the assumptions
Write each belief as “We believe that…”, then circle its type, importance, and how much evidence you already have.
Type: Desirability · Usability · Feasibility · Viability · Importance: High · Medium · Low · Evidence: Strong · Weak · none
Map: importance × evidence
Place each assumption in a quadrant. One corner matters most — high importance, low evidence.
High importance · low evidence
Your leap-of-faith assumptions — test first
High importance · strong evidence
Safe-ish to build on — keep an eye on it
Low importance · low evidence
Don’t waste a test here yet
Low importance · strong evidence
Ignore — move on
The riskiest assumption test card
One card per assumption, riskiest first. The success criterion goes on the card before the test runs — that’s the whole trick.
Next assumption? Print this page again — one card per test keeps the record honest.
Pick the right test
Name the assumption’s type and the test picks itself — a desirability doubt needs customers, a feasibility doubt needs a spike.
Desirability
Do customers actually want this?
Test with: Interviews, fake-door tests, landing pages
Usability
Can people figure out how to use it?
Test with: Prototype tests, usability sessions
Feasibility
Can we build and run it, with our team and constraints?
Test with: Technical spikes, throwaway prototypes
Viability
Should we build it — does it work for the business?
Test with: Pricing tests, business-model math
Watch-fors
The four ways assumption tests most often go sideways.
Testing the comfortable assumption
It’s tempting to test what’s easy to measure. If the result couldn’t change your plan, you tested the wrong assumption.
Deciding success after the results
Post-hoc, any result can be argued into a pass. Write the criterion first so the test is allowed to fail.
Building an MVP to “test”
The smallest test is rarely a build: a fake door, five interviews, or a spreadsheet beats four sprints of code.
“Inconclusive” quietly becomes “validated”
A weak signal is a prompt to sharpen the test, not permission to proceed. Say which one it was, out loud.
Give your assumptions a living home
In Outcomify, assumptions are first-class nodes under the solutions that depend on them — tracked as untested, validated, or invalidated, with the evidence attached, on the same tree as your outcomes and opportunities.