“Observed power”, “Post hoc Power”, and “Retrospective power” all refer to the statistical power of a statistical significance test to detect a true effect equal to the observed effect. In a broader sense these terms may also describe any power analysis performed after an experiment has completed. Importantly, it is the first, narrower sense that […] Read more...| Blog for Web Analytics, Statistics and Data-Driven Internet Marketing | Analy...
The above is a question asked by some practitioners of A/B testing, as well as a number of their clients when examining the outcome of an online controlled experiment. It may be raised regardless if the outcome is statistically significant or not. In both cases the fact the observed effect in an A/B test is […] Read more...| Blog for Web Analytics, Statistics and Data-Driven Internet Marketing | Analy...
One topic has surfaced in my ten years of developing statistical tools, consulting, and participating in discussions and conversations with CRO & A/B testing practitioners as causing the most confusion and that is statistical power and the related concept of minimum detectable effect (MDE). Some myths were previously dispelled in “Underpowered A/B tests – confusions, myths, and reality”, “A comprehensive guide to observed power (post hoc power)”, and other works. Yet others remain.| Blog for Web Analytics, Statistics and Data-Driven Internet Marketing | Analy...
How long does a typical A/B test run for? What percentage of A/B tests result in a ‘winner’? What is the average lift achieved in online controlled experiments? How good are top conversion rate optimization specialists at coming up with impactful interventions for websites and mobile apps?| Blog for Web Analytics, Statistics and Data-Driven Internet Marketing | Analy...