Conciseness

The body is mostly efficient tables and decision rules, but includes unnecessary material: a Wikipedia definition of Simpson's paradox and explanations of novelty/primacy that Claude already knows, plus the Kohavi citation with ISBN repeated three times and the reference set enumerated twice (in Step 6 prose and again in the References section). It sits at 'mostly efficient but includes some unnecessary explanation or could be tightened', above the 2 anchor's pervasive padding but below the 4 anchor's minor trims.

Actionability

For an instruction-only skill the guidance is largely concrete: per-step decision tables with pass criteria, specific thresholds ("two full weeks", "> 20% of users"), a segment-detection procedure, and a fully worked example with real numbers ending in a ship decision. It falls short of 5 because some steps remain directive rather than executable (e.g., "List all experiments running in the same user population" with no query or method), and the actual computation is delegated to a reference file.

Workflow Clarity

Six explicitly ordered steps with a declared hard-stop rule ("Each step has a hard stop: if a step blocks, do not proceed to the next"), per-step pass/block criteria, a numbered guardrail check with STOP conditions, explicit remedies when a check fails (isolate and re-run, factorial model, block ship; accepted-risk-or-extend for guardrail alerts), and a worked example running the full sequence. This matches the 5 anchor's explicit validation steps, feedback loops, and checklists; the operation is interpretive, not destructive/batch, so no cap applies.

Progressive Disclosure

SKILL.md is a clear overview with well-signaled, one-level-deep markdown links, and every referenced file exists with substantive content. It falls short of 5 due to minor organization gaps: two bundle files (significance-anti-patterns.md, significance-output-example.md) are never referenced or discoverable from the body, and the Step 6 reference paragraph is a dense parenthetical that duplicates the References section.

Specificity

The description lists multiple concrete actions — "Computes significance per metric with multiple-comparison correction, reads confidence intervals, checks novelty, interactions, Simpson's paradox, guardrails and stop-early rules" — with comprehensive coverage of the skill's capabilities. It matches the anchor for multiple specific concrete actions rather than the 4 anchor, which would require minor gaps in coverage.

Completeness

Both what and when are explicit: an "Use when an A/B test result is read for a ship decision..." trigger clause with concrete conditions (dashboard, small sample, many metrics), followed by a full enumeration of what the skill does. This matches the 5 anchor (clear, explicit what AND when with concrete trigger phrases), not the 4 anchor where the 'when' could be more specific.

Trigger Term Quality

Good natural keyword coverage: "A/B test result", "ship decision", "dashboard", "small sample", "many metrics", "confidence intervals", "guardrails" are phrases a user would naturally say. A few common variations are missing (e.g., "experiment results", "significance", "p-value", "lift"), which places it just below the comprehensive-synonyms anchor of 5.

Distinctiveness Conflict Risk

The niche is clear (interpreting a finished experiment's result for a ship/no-ship call), and triggers like "Simpson's paradox" and "guardrails" are distinctive. However, the body names a companion skill `ab-test-validity-checklist` covering adjacent A/B-testing territory, so there is minor overlap risk with a closely related skill — the 4 anchor — rather than the minimal-conflict 5 anchor.