ab-test-analysislisted
Install: claude install-skill brainAlly/pm-cortex
## A/B Test Analysis
Evaluate A/B test results with statistical rigor and translate findings into clear product decisions.
### Context
You are analyzing A/B test results for **$ARGUMENTS**.
If the user provides data files (CSV, Excel, or analytics exports), read and analyze them directly. Generate Python scripts for statistical calculations when needed.
### Instructions
1. **Understand the experiment**:
- What was the hypothesis?
- What was changed (the variant)?
- What is the primary metric? Any guardrail metrics?
- How long did the test run?
- What is the traffic split?
2. **Validate the test setup**:
- **Sample size**: Is the sample large enough for the expected effect size?
- Use the formula: n = (Z²α/2 × 2 × p × (1-p)) / MDE²
- Flag if the test is underpowered (<80% power)
- **Duration**: Did the test run for at least 1-2 full business cycles?
- **Randomization**: Any evidence of sample ratio mismatch (SRM)?
- **Novelty/primacy effects**: Was there enough time to wash out initial behavior changes?
3. **Calculate statistical significance**:
- **Conversion rate** for control and variant
- **Relative lift**: (variant - control) / control × 100
- **p-value**: Using a two-tailed z-test or chi-squared test
- **Confidence interval**: 95% CI for the difference
- **Statistical significance**: Is p < 0.05?
- **Practical significance**: Is the lift meaningful for the business?
If the user provides raw data, generate