# Assumptions and Decision Log

Keep supporting and disconfirming evidence attached to a decision.

Built Into Work | Vic Akosile | Version 1.0 | October 5, 2026

For: Sponsors, product owners, and working teams
Use when: When an important decision depends on uncertain information
Suggested time: 15 minutes

Use synthetic or authorized information. Keep sensitive work in approved tools. A named person owns each decision. These tools support discussion and planning; they are not validated assessments.

## 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?

Your response:

________________________________________________________________

### Supporting evidence

What observation supports that belief?

Your response:

________________________________________________________________

### Disconfirming evidence

What would show the assumption is wrong?

Your response:

________________________________________________________________

### Test and owner

What can you inspect or try next?

Your response:

________________________________________________________________

### Decision and residual uncertainty

Continue, change, defer, or stop? What remains unknown?

Your response:

________________________________________________________________

### Review date

When will you revisit it?

Your response:

________________________________________________________________

## Completed companion example

All organizations, workflows, numbers, and results in these examples are fictional and provided for learning. Targets are proposed decision criteria, not validated standards or promised outcomes.

**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.

## Working record

Owner:
Review date:
Decision:
Evidence still needed:

Original guide: https://builtinto.work/resources/assumptions-decision-log