# Articles onStatistical significance

Articles on the topic of statistical significance in online A/B tests. What is significance, how to use it in various advanced scenarios and how to avoid the many misinterpretations, misuses, and abuses of p-values and confidence intervals.

## The Importance of Statistical Power in Online A/B Testing

What is Statistical Power? In null-hypothesis statistical testing (NHST) – the procedure most commonly applied in A/B tests, there are two types of errors that practitioners should care about, type I and type II errors. Type I is the probability of the test procedure to falsely reject a true null hypothesis. Type II error is […] Read more…

## 5 Reasons to Go Bayesian in AB Testing – Debunked

As someone who spent a good deal of time on trying to figure out how to run A/B tests properly and efficiently, I was intrigued to find a slide from a presentation by VWO®’s data scientist Chris Stucchio, where he goes over the main reasons that caused him and the VWO® team to consider and […] Read more…

## The Bane of AB Testing: Reaching Statistical Significance

Now, this is not a new topic on this blog. I’ve discussed the issue of optional stopping based on “achieving” or “reaching” statistical significance in my Why Every Internet Marketer Should be a Statistician post more than two years ago and others have touched on it as well – both before and after me. However, the issue […] Read more…

## Bayesian AB Testing is Not Immune to Optional Stopping Issues

Fantasy vs the Real World: Naive Bayesian AB Testing vs Proper Statistical Inference This post is addressed at a certain camp of proponents and practitioners of A/B testing based on Bayesian statistical methods, who claim that outcome-based optional stopping, often called data peeking or data-driven stopping, has no effect on the statistics and thus inferences […] Read more…

## Overview of Books on Conversion Optimization, Web Analytics, SEO & PPC

This overview is a little different than most overeviews out there. It will focus on three specific basic statistical concepts and would show if and how well they are explored in 18 of the top books on Conversion Optimization, A/B testing, web analytics, SEO & PPC/AdWords. The three concepts this review focuses on are statistical […] Read more…

|

## Why Every Internet Marketer Should Be a Statistician

I’ll start this post right with the punch line: Internet marketing at its current state is dominated by voodoo magic. There, I’ve said it, and I’ve said it in bold italic so you know it must be true. Internet marketing is not as data-driven as most of us have been led to believe, it is […] Read more…

#### Browse by year

The book on user testing

Take your A/B testing program to the next level