P96StatisticsIntermediateCalculate10 min
Calculate Uncertainty for a Difference in Conversion Rates
Calculate approximate uncertainty around a difference in conversion rates.
#calculate#conversion#confidence interval
Scenario
Variant A has 120 conversions from 2,000 visitors (6.0%). Variant B has 150 conversions from 2,000 visitors (7.5%). Use SE(diff) = sqrt(pA(1-pA)/nA + pB(1-pB)/nB).
Problem statement
Calculate the difference, approximate standard error, and a rough 95% interval using difference +/- 1.96 * SE. Interpret the uncertainty.
Your Task
- Calculate the rate difference.
- Apply the supplied standard-error formula.
- Interpret precision without overstating the result.
Related Concepts
Standard errorA/B testingConfidence intervals
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