## 1. Book Identity ### *Accelerate: The Science of Lean Software and DevOps* ### Nicole Forsgren, Jez Humble, Gene Kim, 2018 ### Foundation for the DORA research programme ## 2. The Four Key Metrics ### Deployment Frequency ### Lead Time for Changes ### Mean Time to Restore (MTTR) ### Change Failure Rate ## 3. Velocity vs Stability ### Velocity metrics: Deployment Frequency + Lead Time for Changes ### Stability metrics: MTTR + Change Failure Rate ### High-performing teams excel on both axes simultaneously ## 4. Predictive Validity ### The four metrics predict organisational performance (profitability, market share, productivity) ## 5. Why It Matters Now (2026 Context) ### Old engineering-velocity metrics (story points, lines, PR count) are easily gamed by AI agents ### The DORA Four remain meaningful because they measure *delivered outcomes* ### Per-merged-PR token cost joins them as the new agentic-era metric ## 6. Anti-metrics (to ignore) ### Lines of code (any direction) ### PR count ### "AI-assisted code %" (almost everything is now) ### Self-reported "time saved" estimates ### References - https://itrevolution.com/product/accelerate/ - https://dora.dev/guides/dora-metrics-four-keys/ - https://cloud.google.com/blog/products/devops-sre/using-the-four-keys-to-measure-your-devops-performance