Conciseness

The body is token-efficient by construction — dense tables, checklists, and bullet fragments with almost no filler. The exception is the p-value/confidence-interval tutorial paragraph in 'Statistical Significance,' which explains statistical definitions Claude already knows and could be trimmed to just the practice guidance. Anchor 4, not 5, because of that over-explained stretch.

Actionability

Fully concrete for an instruction-only skill: a copy-paste hypothesis template with weak/strong examples, a numeric sample-size quick-reference table (e.g., '3% baseline, 20% lift → 12k/variant'), the ICE formula, named tools per implementation style, and a fill-in playbook template with exact fields. Common cases are covered with specifics; absence of code is not penalized per the rubric's instruction-skill note.

Workflow Clarity

The sections follow the test lifecycle (assess → hypothesize → design → size → run → analyze → document) and the Experiment Loop is explicitly numbered 1–6. Validation is explicit: a 6-item pre-launch checklist ('Tracking verified,' 'QA completed on all variants'), during-test monitoring with DO/Avoid, and a 6-item analysis checklist with error-recovery guidance (mixed signals → check data quality, confirm segments in a new test; stop if guardrails go significantly negative). Not a destructive/batch skill, so no cap applies.

Progressive Disclosure

Both references exist, are one level deep, and are purpose-signaled ('For detailed sample size tables and duration calculations: See references/sample-size-guide.md'; 'For templates: See references/test-templates.md'), with quick tables inline and the bulk split out. Falls short of anchor 5 because the ~85-line Growth Experimentation Program section is a self-contained unit that could live in its own reference file, leaving the main body longer than a lean overview.

Specificity

Concrete actions are named — 'plan, design, or implement an A/B test or experiment' and 'build a growth experimentation program' — giving several specific capabilities. Not a 5 because the analysis/interpretation work the skill clearly supports is absent from the action list; not a 3 because more than 1-2 actions are covered.

Completeness

Explicitly answers both what ('plan, design, or implement an A/B test or experiment, or build a growth experimentation program') and when ('Also use when the user mentions…', 'Use this whenever someone is comparing two approaches…') with concrete trigger phrases, and adds disambiguation routing ('For tracking implementation, see analytics. For page-level conversion optimization, see cro.').

Trigger Term Quality

Eighteen-plus natural quoted phrases users would actually say ('A/B test,' 'split test,' 'should I test this,' 'which version is better,' 'test two versions,' 'how long should I run this test,' 'ICE score,' 'experiment playbook') plus synonyms, program-level terms, and scenario framings ('comparing two approaches and wants to measure which performs better'). Comprehensive coverage matches the top anchor.

Distinctiveness Conflict Risk

Clear experimentation niche with explicit routing to sibling skills, but the very broad quoted terms 'experiment,' 'hypothesis,' and 'test this change' could over-trigger in non-growth contexts (e.g., testing a code change). Minor overlap risk with closely related skills — anchor 4, not 5.