Assumptions and Decision Log
Keep supporting and disconfirming evidence attached to a decision.
Use this guide to structure a discussion, then record your answers in the editable template or printable PDF. Use synthetic or authorized information. A named person owns each decision.
Separate what you know from what you believe
Record one consequential assumption per row. Make the test observable, and look for evidence that would overturn the assumption.
- Decision and assumption
- What are you deciding, and what must be true?
- Supporting evidence
- What observation supports that belief?
- Disconfirming evidence
- What would show the assumption is wrong?
- Test and owner
- What can you inspect or try next?
- Decision and residual uncertainty
- Continue, change, defer, or stop? What remains unknown?
- Review date
- When will you revisit it?
See a completed companion example
- Decision and assumption
- Pilot policy drafting; assume source lookup is a major contributor to handling time.
- Supporting evidence
- Analysts report repeated policy searches; timed baseline still needed.
- Disconfirming evidence
- Most handling time comes from missing context rather than lookup.
- Test and owner
- Service-desk lead times a consistent sample over two weeks.
- Decision and residual uncertainty
- Defer time-saving claim until baseline is measured; quality benefit remains a separate hypothesis.
- Review date
- At the baseline review, two weeks after kickoff.
Record the next decision.
What will you do next, who owns it, and when will you review the evidence? Keep unresolved assumptions visible.