A discipline for designing experiments (A/B tests, multivariate, holdouts) so the results actually answer the question you asked. Hypothesis writing, sample size, duration, segment analysis, running discipline, matching a result to a pre-committed decision rule, and the common failure modes that produce confidently wrong shipping decisions.
Install
npx skills add rampstackco/claude-skills --skill experiment-designnpx skills add rampstackco/claude-skills --skill experiment-design -a claude-code -gnpx skills add rampstackco/claude-skills --skill experiment-design -a codex -ggemini skills install https://github.com/rampstackco/claude-skills.git --path skills/experiment-designgh skill install rampstackco/claude-skills experiment-designgit clone --depth 1 https://github.com/rampstackco/claude-skills /tmp/rampstackco__claude-skills
mkdir -p ~/.claude/skills ~/.agents/skills
cp -R /tmp/rampstackco__claude-skills/skills/experiment-design ~/.claude/skills/experiment-design # Claude Code
cp -R /tmp/rampstackco__claude-skills/skills/experiment-design ~/.agents/skills/experiment-design # Codex, Cursor, Gemini CLI, Copilot, OpenCode