Direct answer
The short version.
A marketing decision log is a chronological record of evidence, interpretation, action, owner and review condition. It preserves the reasoning behind campaign changes so future teams do not repeat the same uncertainty.
Key takeaways
Keep these three decisions.
- Record interpretation, not screenshots alone.
- Attach owners and review triggers.
- Link decisions to campaign and asset identifiers.
The operating problem
Dashboards show what happened but rarely why a budget moved, an audience was paused or a claim was changed. Decisions disappear into meetings and chat, making later performance impossible to interpret and causing old tests to be relaunched without their original context.
A practical system
For every material change, record the date, question, evidence window, known limitations, decision, expected effect, owner and next review trigger. Link the entry to campaign and asset identifiers. Keep the log concise enough to use during live reviews rather than turning it into another retrospective report.
What to measure next
Audit repeated tests, unexplained changes and time spent reconstructing history. The log works when teams can answer why the account is configured this way, what they currently believe and which new evidence would change that belief.
Primary and authoritative references
Sources used for context.
Frequently asked questions
Two useful follow-ups.
What belongs in a marketing decision log?
Include the question, evidence, limitations, action, owner, expected result and condition for review or reversal.
Is a decision log the same as a change history?
No. A change history says what changed; a decision log explains why it changed and what the team expected.