> ## Documentation Index
> Fetch the complete documentation index at: https://docs.marketer.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Diagnose a performance change

> Investigate a performance increase or decline by testing competing explanations against connected data.

Use this pattern when a metric moved enough to require an explanation. Ask Marketer to test several plausible causes instead of confirming the first story that fits.

## Gather the inputs

* The metric and size of the change.
* The exact date window and baseline.
* The channel, campaign, product, creative, or audience in scope.
* Known business events such as a promotion, inventory change, price change, or site incident.
* Any limits on the sources Marketer should use.

## Starting request

```text theme={null}
Investigate why [metric] changed by [amount] for [scope] between [current period] and [baseline].
Test at least three explanations across the connected data, including changes in delivery, conversion behavior, creative mix, and product or site context where available.
For each explanation, show supporting and conflicting evidence, note missing data, and rank confidence.
Finish with the smallest safe follow-up check. Do not make external changes.
```

## Review the diagnosis

Look for an evidence trail rather than a confident narrative. A strong diagnosis:

* Uses the same scope for each comparison.
* Separates platform-reported data from commerce or site data.
* Shows which explanation best fits and what would disprove it.
* Calls out missing or stale data.
* Recommends a reversible next check before a material action.

<Warning>
  Do not turn a diagnosis into a campaign change until you have reviewed the affected entity, the proposed setting, and the approval path for that action.
</Warning>

If the result needs another data source, visit [Integrations](/integrations/overview). If it needs business context, add it through [Knowledge and Skills](/product-guides/knowledge-and-skills).


## Related topics

- [Performance and custom views](/product-guides/analytics-performance-and-views.md)
- [Analyze recent performance](/templates-use-cases/analyze-performance.md)
- [Templates and use cases](/templates-use-cases/overview.md)
- [Analytics](/product-guides/analytics.md)
- [Creative performance](/product-guides/analytics-creative-performance.md)