What is MDE (minimum detectable effect)?

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Answer

$Smallest effect size the experiment can detect with a target power (usually 0.8) given the sample size and α.$
$Computed via power formula.$
$Practical use: 'with N=10000 users per arm at α=0.05 and power 0.8, the MDE is a 2% lift'.$
$If your product intuition says the effect might be 1%, you need to grow n.$
$Cornerstone of A/B testing capacity planning.$

Check yourself — multiple choice

Same as p-value
Smallest effect detectable at target power given n and α; foundation of A/B test sizing decisions
Only for regression
Not useful

MDE: smallest effect a study can detect at target power; A/B sizing cornerstone.

#hypothesis-testing#power#ab-testing

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