Minimum Detectable Effect Calculator
Estimate the smallest conversion-rate lift an A/B test plan can reliably detect.
At a glance
- Computes
- Effect at chosen power, or the nearest attainable boundary for the selected design.
- You supply
- Baseline rate, total sample size, split, alpha, power, tails, and direction.
- Use when
- Traffic is fixed and you need the chosen-power effect or nearest attainable boundary.
- Not for
- Choosing a sample size for an effect you already decided matters. Power and Sample Size Calculator
Minimum detectable effect
Enter values
Uses total sample size and visible split.
Absolute effect against Total sample size
| Metric | Value |
|---|
Solve d where power(pA, pB, nA, nB, alpha) equals requested power
How?
How this is calculated
This calculator solves the two-independent-proportions z-test power equation. It uses pooled variance under the null, non-pooled variance under the alternative, and the visible traffic split to derive A and B sample sizes.
Formula: Solve d where power(pA, pB, nA, nB, alpha) equals requested power
Sources
- statsmodels power_proportions_2indep. statsmodels. Retrieved .
- statsmodels samplesize_proportions_2indep_onetail. statsmodels. Retrieved .
Method last reviewed