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AliMaleki
Level 4
April 17, 2018
Solved

50/50 Test Actually 56/44

  • April 17, 2018
  • 2 replies
  • 3487 views

Why is it that my 50/50 A/B tests are often lopsided with more Experience A visitors?

Ali

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Best answer by russpainter

This is basic statistics. If you flip a coin 100 times you could potentially get lopsided heads or lopsided tails. If you continue to flip a coin a million times you should experience a close 50/50 percentage of time and the more times you flip.

You can tell when an a/b test has normalized and the noise of adding a new experience has leveled out when your experiences come back to an even split.

This is the principal behind A/A tests as well. If you run an A/A/B Test you know you can call it when you have significance and the A cells have leveled to 50/50 on traffic and conversion.

Let me know if you have questions

Russ

2 replies

russpainterAccepted solution
Level 3
April 17, 2018

This is basic statistics. If you flip a coin 100 times you could potentially get lopsided heads or lopsided tails. If you continue to flip a coin a million times you should experience a close 50/50 percentage of time and the more times you flip.

You can tell when an a/b test has normalized and the noise of adding a new experience has leveled out when your experiences come back to an even split.

This is the principal behind A/A tests as well. If you run an A/A/B Test you know you can call it when you have significance and the A cells have leveled to 50/50 on traffic and conversion.

Let me know if you have questions

Russ

AliMaleki
AliMalekiAuthor
Level 4
April 17, 2018

This makes perfect sense. Thanks,

Ali