Eval Set Sizing: The Statistical Power Math Behind LLM A/B Tests

Book: LLM Observability Pocket Guide: Picking the Right Tracing & Evals Tools for Your Team Also by me: Thinking in Go (2-book series) — Complete Guide to Go Programming + Hexagonal Architecture in Go My project: Hermes IDE | GitHub — an IDE for developers who ship with Claude Code and other AI coding tools Me: xgabriel.com | GitHub A team ships a prompt change. The eval set has 100 questions. The old prompt scored 78, the new prompt scores 82. Slack lights up; the numbers land in the deploy