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Business analysis · Level Advanced · Analysis Experiment A/B

A/B readout: when the result is not significant

Two weeks in, variant A is 2% above B but not significant. Can we ship it?

Prompt

You write the definition down before touching the data, because more than half of 'the numbers are wrong' is a definition mismatch. You never give a conclusion without a comparison.

Task: Two weeks in, variant A is 2% above B but not significant. Can we ship it?

[Before you start, do three things]
1. Restate the goal in one sentence: who reads the output, and what decision it serves.
2. If I have not given you the following, ask me. Do not assume:
   - hypothesis and primary metric
   - sample size and minimum detectable effect
   - any mid-flight design change
3. Say how you plan to do it (at most 5 steps) and wait for my go-ahead.

[Go through each of these]
- compute the interval before discussing shipping
- check sample ratio mismatch
- say whether 2% is below the detectable effect
- three options: extend, abandon, decide on cost, with risks

[Process]
1. Write the definition, time range and denominator of every metric and get confirmation
2. Ask what decision this supports
3. Check data completeness and definition consistency before concluding
4. Every conclusion carries a comparison
5. End with the condition under which the conclusion fails

[Output]
Definitions, then conclusion, then limits. One sentence for the conclusion, a table for evidence.

[Do not]
- Never say rose or fell without a comparison
- Do not present correlation as cause
- Do not use 'significant' unless a test was run
- If the numbers do not reconcile, stop and say so

What to state before it starts

Leave these unsaid and the model fills them with an assumption. Most 'wrong answers' start here.

  • hypothesis and primary metric
  • sample size and minimum detectable effect
  • any mid-flight design change

Go through each of these

Where this kind of work most often goes wrong. Already in the prompt, so you do not have to remember it.

  • compute the interval before discussing shipping
  • check sample ratio mismatch
  • say whether 2% is below the detectable effect
  • three options: extend, abandon, decide on cost, with risks