Write the hypothesis, the metric, and the stopping rule before launch.
A plan for one A/B test that fixes what you are testing and how you will decide, before anyone sees a result.
A weak test usually fails before it starts. The hypothesis is a hunch, the metric is picked after the results arrive, and the test ends when the graph looks good. Stopping on a good day proves very little.
A/B Test Plan writes the hypothesis with its reason, one primary metric defined exactly, guardrails, and the control and variant. It leaves the sample size and stopping rule as items to confirm with whoever owns your analytics, records what they say, and pre-writes what you will do for each outcome.
What it produces.
- →A hypothesis in if, then, because form
- →One primary metric and one to three guardrails, defined exactly
- →A stopping rule slot filled with what your analytics owner confirms
- →A decision for each outcome, including no difference
- ✦Growth leads and marketers planning a test
- ✦Product managers about to ship a change to a share of users
- ✦Anyone who wants a test plan others can check afterward
- →ab-test-plan.zip: a native Claude Skill. Upload to Settings → Skills in Claude, or unzip to
~/.claude/skills/ - →ab-test-plan-skill.md: plain markdown. Works in ChatGPT Custom GPTs, Gemini, Claude Projects, agent system prompts, anywhere
- →A README inside the zip with install steps for Claude, ChatGPT, and Gemini
No subscription · free updates within v1.x
Works as a Claude Skill (.zip) and as a plain .md for ChatGPT, Gemini & every LLM
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Before you buy.
How is this different from just asking Claude directly?
Asked cold, Claude may give you sample size figures and a significance threshold as if they applied to your traffic. This plans the test, leaves those numbers for your analytics owner to confirm, and makes sure the metric and decisions are set before launch.
How is this different from a Tool?
Playbooks are systematically produced to a fixed template and priced accordingly ($12.99). Tools are hand-built, one at a time, and go deeper ($39 to $199). A Playbook gives you a reliable method for routine work; a Tool is for when the judgment matters more than the format.
Will this work with ChatGPT, Gemini, and other LLMs?
Yes. You get a native Claude Skill (.zip) that auto-invokes in Claude, plus a plain .md you can paste into a ChatGPT Custom GPT, a Gemini system prompt, or any LLM. The procedure travels with the file.
Can I share this with my team?
It's licensed for your own personal and professional use. The output it produces is yours to circulate. To put the Playbook itself in the hands of a whole team, email hello@authority.md about team licensing.
What if it doesn't work for me?
If the file hasn't been delivered, or arrives defective or empty, we refund in full: see our refund policy.