# What is Root Cause Analysis (RCA)?

> Finding the underlying reason a problem happened, not just its symptoms.

Canonical: https://www.decimal.app/glossary/root-cause-analysis · Last reviewed: 2026-09-23

Root cause analysis is a structured process to identify the fundamental cause of an issue, using methods like the five whys or a timeline review, so the fix prevents recurrence.

## Why it matters

Fixing symptoms closes one ticket. Fixing the root cause closes every future ticket like it.

## Best practices

1. Follow the evidence. Logs, traces, diffs, and data, in that order.
2. Ask why until it's a system issue. Stop when you reach something you can change.
3. Share findings with support. So they recognize the pattern next time.

## How Decimal helps

Decimal produces a cited root cause for technical tickets, which engineers can verify and act on instead of starting from scratch.

## Related terms

- [Agentic Investigation](https://www.decimal.app/glossary/agentic-investigation): An AI agent working a ticket the way an engineer would: hypothesis, evidence, conclusion.
- [Postmortem](https://www.decimal.app/glossary/postmortem): A blameless review of what went wrong and how to prevent it recurring.
- [Regression](https://www.decimal.app/glossary/regression): A bug where something that used to work stops working after a change.
- [Mean Time to Resolution (MTTR)](https://www.decimal.app/glossary/mttr): The average time from when an issue is reported to when it's fixed.

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