A/B Testing

The Most Powerful Way to Turn Clicks Into Customers

The average conversion rate—the rate at which visitors convert into customers—across the web is only 2%. That means it’s likely that 98% of visitors to your website won’t end up converting into customers.

What’s the solution? A/B testing.

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Become a Hero at Your Organization

A/B testing is the simple idea of showing several different versions of a web page to live traffic, and then measuring the effect each version has on visitors. Marketers and web professionals will become obsolete if they don’t embrace a data-driven approach to decision making. This book shows you how, no matter your technical expertise.

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Book Endorsements

"Dan and Pete are changing the way business is done and decisions are made. By pulling together concrete examples of how A/B testing has made an impact, they are inspiring a new generation of companies to make thoughtful, data-driven decisions. Their new book is smart, valuable and proves just how indispensable A/B testing is today."


"A practical and readable guide to get the most out of your online marketing tests. Get it before your competitors do!"

— TIM ASH, CEO of SiteTuners, bestselling author of Landing Page Optimization, and chair of Conversion Conference

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Optimization Events

Meet marketers around the world who are making A/B testing part of their daily process. Hear from industry experts and conversion optimization evangelists about why adopting a data-driven approach to marketing is changing the way business is done.

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About the Authors

Authors Dan Siroker and Pete Koomen are co-founders of Optimizely, the leading A/B testing platform used by more than 5,000 organizations across the world.

Dan Siroker

Dan Siroker is the co-founder and CEO of Optimizely. The inspiration for Optimizely came from Dan's experience as the Director of Analytics for the 2008 Obama Presidential campaign. Optimizely is the product Dan wishes he had back then to make it easy for anybody to do A/B testing. In 2012, Forbes named Dan one of the Top 30 under 30 in Technology. Dan was formerly a product manager for Google Chrome and AdWords.

Pete Koomen

Pete Koomen is the co-founder and President of Optimizely. After earning his M.S. in Computer Science from the University of Illinois at Urbana Champaign, Pete joined Google as a product manager where he helped launch and grow Google App Engine to more than 150,000 developers. In 2009, Pete teamed up with Dan to start their first company, CarrotSticks, an online math game for kids. Less than a year later, Pete and Dan created Optimizely during the YCombinator winter 2010 class. Pete runs product, engineering, and design at Optimizely.