Mostly efficient tabular reference material, but it spends tokens restating concepts Claude already knows (e.g. "95% confidence = p-value < 0.05", "The Peeking Problem", and truisms like "Otherwise you don't know what worked"), so it could be tightened.

As an instruction-only skill it provides concrete, copy-paste-ready assets: a fill-in hypothesis template with a worked example, a sample-size quick-reference table, named tools, and pre-launch/analysis checklists.

The design→run→analyze flow is clearly sequenced, with an explicit pre-launch checklist (including "Tracking verified", "QA completed") and a six-step analysis checklist serving as validation checkpoints.

SKILL.md acts as an overview and pushes detail to two real, one-level-deep references — references/sample-size-guide.md and references/test-templates.md — each clearly signaled with context and a markdown link.

Lists three concrete actions — "plan, design, or implement an A/B test or experiment" — matching the multiple-specific-actions anchor; it is not merely a domain label.

Answers both what ("plan, design, or implement an A/B test or experiment") and when with an explicit "Use when the user mentions..." trigger clause, satisfying the full what-and-when anchor.

Strong natural-language coverage: "A/B test," "split test," "experiment," "test this change," "variant copy," "multivariate test," and "hypothesis" are all phrasings a user would actually say.

Occupies a clear experimentation niche with distinctive triggers and even disambiguates from a sibling skill via "For tracking implementation, see analytics-tracking," reducing conflict risk.