

Deriving formulas for the expected sample size needed in A/B tests - zenburnmyface
http://camdp.com/blogs/number-samples-needed-b-test

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jdlshore
I'm not qualified to comment on Cam's math, but Evan Miller's tools [1] are my
go-to source for calculating sample sizes and significance. How does this
differ? (If it does.)

[http://www.evanmiller.org/ab-testing/sample-
size.html](http://www.evanmiller.org/ab-testing/sample-size.html)

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yetanotherphd
That looks right to me. This is a very important calculation to do in order to
avoid getting 100x the number of samples that you really need.

Essentially the same calculation applies to classification error.

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ska
The real (and all to common to run into ) problem isn't having 100x the
samples you really need, it is having 1/10 the samples you really need... And
not knowing that.

