🍪 CRO Bites #10: Sequential Testing - 7 Tech Companies Sharing Insights

Hi there 👋

We all know the standard rule of A/B testing: don’t peek!

However, there has been a noticeable shift in the industry over the years. Sequential testing is gaining massive traction by solving the age-old conflict between statistical rigor and the need for speed.

What is particularly exciting is the wealth of practical knowledge that has been shared in recent years. Several tech companies have published excellent articles explaining how they incorporate sequential testing into their experimentation programmes.

We curated the most valuable blog articles from 7 leading tech companies:

1. Uber (2018) | Building Automated Feature Rollouts on Robust Regression Analysis

2. DoorDash (2022) | Meet Dash-AB: The Statistics Engine of Experimentation at DoorDash

3. Spotify (2023)

   1. Choosing a Sequential Testing Framework — Comparisons and Discussions

   2. Bringing Sequential Testing to Experiments with Longitudinal Data (Part 1): The Peeking Problem 2.0

   3. Bringing Sequential Testing to Experiments with Longitudinal Data (Part 2): Sequential Testing

4. Booking.com (2023) | Sequential Testing at Booking.com

5. GetYourGuide (2023) | How Sequential Testing Accelerates Our Experimentation Velocity

6. Netflix (2024)

   1. Sequential A/B Testing Keeps the World Streaming Netflix - Part 1: Continuous Data

   2. Sequential A/B Testing Keeps the World Streaming Netflix - Part 2: Counting Processes

7. Photoroom (2025) | Why sequential testing is the right way to experiment at the speed of PLG apps like Photoroom

Special thanks to all authors of the individual blog articles for sharing your expertise!

Looking for more engineering insights? We curate these and other experimentation blogs directly at Conversion Stash.

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This book will help you navigate the statistical jungle of jargon & formulas. You will understand the advantages and limitations of statistical approaches for assessing the uncertainty of data from online controlled experiments. You will learn how to design efficient statistical tests and to adapt statistical models in a number of practical scenarios, primarily from e-commerce A/B testing.

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50 Experimentation Interview Questions
Hiring for CRO or preparing for your next role? This list of 50 essential questions will help assess candidates’ expertise in experimentation, analytics, and optimization strategy.

Test Planning + Test Analysis Templates (by Gerda Thomas & Ryan Thomas)
Two Google Sheets templates for pre- and post-analysis of AB tests.

CRO Glossary Cheatsheet
Master the language of experimentation with our CRO Glossary Cheatsheet. This quick reference guide covers 100+ key terms, helping you navigate A/B testing, statistical significance, and optimization frameworks like a pro.

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A big THANK YOU to some outstanding contributors who help enrich the platform:

• Hannah Gallus – Marketing Manager @ Kameleoon

• Henrik Bylund Ramirez – CRO Strategist @ VELUX

• Josh Roberts – CRO Consultant (Freelancer)

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As the year 2025 comes to a close, we have put together a rundown of the experiments that are in the works for 2026.

Did you know? You can easily add the Experimentation Events calendar to your Google, Outlook or Apple calendar by clicking this button.

• 🇸🇪 MeasureCamp Malmö | January 17, 2026 | Malmö, Sweden

• 🇬🇧 Experimentation London #9 | January 21, 2026 | London, UK

• 🇩🇰 CROpen Mic #6 | January 27, 2026 | Copenhagen, Denmark

• 🇭🇺 Superweek | February 2-6, 2026 | Budapest, Hungary

• 🇨🇦 UNITE Summit | February 4-6, 2026 | Vancouver, Canada

• 🇳🇱 Optimization Meetup Utrecht #1 | February 5, 2026 | Utrecht, Netherlands

• 🇺🇸 Experimentation Island | February 24-26, 2026 | Georgia, USA

• 🇩🇰 Conversionboost | March 17, 2026 | Copenhagen, Denmark

• 🇳🇱 Emerce Conversion | April 9, 2026 | Amsterdam, Netherlands

• 🇺🇸 Product Analytics Summit | April 15, 2026 | San Jose, USA

• 🇬🇧 Space Academy by ExElite | AI That Works | May 6, 2026 | London, UK

• 🇬🇧 Space Academy by ExElite | Tomorrow’s World Today | May 7, 2026 | London, UK

• 🇬🇧 Circus (formerly known as EXL) | May 11-12, 2026 | London, UK

• 🇩🇪 Growth Minded Superheroes | June 16, 2026 | Frankfurt am Main, Germany

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Find 100+ experimentation related jobs on ExperimentationJobs.com. These jobs are from all over the world, on-site, fully remote or hybrid. Take a look and start pivoting your career.

This week’s featured roles:

• Senior AI Transformation Manager at Miro (Amsterdam, Netherlands)

• Marketing Attribution Experimentation Analyst at Vanguard (USA)

• Senior Media Experimentation Manager – Digital Media at Zalando (Berlin, Germany)

• eCommerce Conversion Rate Optimisation at VANS (Stabio, Switzerland)

• Senior Product Manager II at Strava (Berlin, Germany)

Are you hiring? Submit here

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Stay optimized,
Niklas & Nils from Conversion Stash