An Improvement Decision Log is a simple record of important choices made during an improvement effort and the reasoning behind them.
The purpose is not to document every conversation. It is to preserve decisions that materially affect scope, priority, method, investment, countermeasure, or ownership.
Without a decision log, teams often revisit the same debate because the original reasoning was forgotten.
Record decisions, not discussion
A useful entry should capture the decision, date, decision owner, evidence considered, alternatives rejected, and any follow-up condition.
Decision Rights in Improvement Work helps clarify who has authority to make which types of decisions.
The log should make that authority visible.
Link the decision to evidence
Important decisions should not appear as unsupported opinions.
Examples include selecting one cause to verify, stopping a low-value project, approving a countermeasure, or changing project scope.
Hypothesis-Driven Problem Solving reinforces the discipline of connecting decisions with testable evidence.
Record meaningful alternatives
A strong decision log briefly identifies what other options were considered.
This helps future reviewers understand whether the decision was deliberate, constrained, or temporary.
The goal is not to write a long narrative.
Record assumptions
Some decisions rely on assumptions such as expected demand, available capacity, supplier timing, or estimated benefit.
Improvement Value Hypothesis provides an example of a decision input that may evolve as evidence improves.
When an assumption changes, the decision may need review.
Define revisit conditions
Not every decision should remain permanent.
Possible revisit triggers include new failure evidence, a capital threshold being exceeded, demand changes, or an ineffective countermeasure.
A revisit condition prevents teams from either reopening every decision or protecting a bad decision indefinitely.
Use the log during reviews
Improvement Tollgate Review can use the decision log to understand major scope, risk, and implementation choices made since the previous gate.
This improves continuity when project participants change.
Keep ownership clear
The log should not become a substitute for accountability.
The decision owner remains responsible for the decision. The project leader remains responsible for executing the approved path.
Common mistakes
Recording every minor conversation, writing decisions with no owner, failing to capture evidence, documenting alternatives in excessive detail, never revisiting assumptions, using the log to avoid accountability, and allowing undocumented side decisions to override the formal project path are common mistakes.
Practical sequence
- identify decisions worth preserving.
- record the decision.
- record the owner.
- record supporting evidence.
- note material alternatives.
- record important assumptions.
- define revisit conditions where needed.
- reference the decision during project reviews.
- update status if the decision changes.
- preserve the log with project learning.
The practical lesson
An Improvement Decision Log protects organizational memory.
Good improvement work depends not only on what was decided, but on remembering why the decision made sense at the time.