Testing Mind Map Series: How to Think Like a CRO Pro (Part 89)

Interview with Pieter Boonstra

There’s the experimentation everyone talks about. And then there’s how it actually happens.

We’re hunting for signals in the noise to bring you conversations with people who live in the data. The ones who obsess over test design and know how to secure buy-in even when results are complex.

They’ve built systems that scale. Weathered the failed tests. Convinced the unconvincible stakeholders.

And now they’re here: opening up their playbooks and sharing the good stuff.

This week, we’re chatting with Pieter Boonstra, owner of the fastest-growing CRO agency in the Netherlands, ConversieKracht.

Pieter, tell us about yourself. What inspired you to get into testing & optimization?

When I studied Marketing at university, we learned a lot about consumer psychology and the theory behind buying behavior. Alongside my studies, I did freelance marketing work for a few webshops. I found consumer psychology very interesting. So in the evenings, I started testing those marketing theories with experiments via Google Optimize on my clients’ webshops.

Answer in 5 words or less: What is the discipline of optimization to you?

Create proven business impact

In your opinion, how is AI influencing experimentation?

I think this is really taking off already. I hope that with all the innovation happening, people will soon be able to spend even more time on what they are great at: coming up with solutions for other people. And that AI will help people with everything else around that, such as setting up experiments, analyses, coding, statistics, etc.

Where do you see optimizers in a year from today? Growth teams, product teams, still an independent unit?

That’s a tough one. We work with clients where the marketing department and production are very often jointly responsible for the results. We see those companies grow very quickly.

Talk to us about some of the unique experiments you’ve run over the years.

An experiment I am proud of is one we ran for a client selling organic soups. When I was given a tour of the factory and visited the packaging department, I noticed that the soups coming off the line were packed in boxes of 6. The packers spent a lot of time tearing open those boxes and repacking them into the quantities that a customer had ordered in the webshop, for example, 7, 4, or 2 jars of soup. Based on these insights, we then tested giving webshop visitors a small discount if they ordered 6, 12, or 24 jars. This resulted in a +60% increase in revenue per customer and also meant that many orders could now be shipped directly from the factory without needing to be repacked.

Another great example is for a client selling high-fiber protein bars. From our research, we saw that the biggest “aha moment” for customers was the taste. So once someone had tasted the protein bar, they were sold and became a fan. In addition, we saw in user research that some customers cut the bars in half because otherwise they felt too full. Together with the client, we designed a tasting box with their 5 best-selling flavors, but with the bars being half the size. We tested the tasting box on the homepage. In the A/B test, we saw an uplift of +15% in purchases among new visitors. After that, we measured repeat purchases from customers who bought the tasting box. These were equal to those of regular customers. That was a big win in getting this company to acquire more high value customers.

Cheers for reading! If you’ve caught the CRO bug… you’re in good company here. Be sure to check back often, we have fresh interviews dropping twice a month.

And if you’re in the mood for a binge read, have a gander at our earlier interviews with Gursimran Gujral, Haley Carpenter, Rishi Rawat, Sina Fak, Eden Bidani, Jakub Linowski, Shiva Manjunath, Deborah O’Malley, Andra Baragan, Rich Page, Ruben de Boer, Abi Hough, Alex Birkett, John Ostrowski, Ryan Levander, Ryan Thomas, Bhavik Patel, Siobhan Solberg, Tim Mehta, Rommil Santiago, Steph Le Prevost, Nils Koppelmann, Danielle Schwolow, Kevin Szpak, Marianne Stjernvall, Christoph Böcker, Max Bradley, Samuel Hess, Riccardo Vandra, Lukas Petrauskas, Gabriela Florea, Sean Clanchy, Ryan Webb, Tracy Laranjo, Lucia van den Brink, LeAnn Reyes, Lucrezia Platé, Daniel Jones, May Chin, Kyle Hearnshaw, Gerda Vogt-Thomas, Melanie Kyrklund, Sahil Patel, Lucas Vos, David Sanchez del Real, Oliver Kenyon, David Stepien, Maria Luiza de Lange, Callum Dreniw, Shirley Lee, Rúben Marinheiro, Lorik Mullaademi, Sergio Simarro Villalba, Georgiana Hunter-Cozens, Asmir Muminovic, Edd Saunders, Marc Uitterhoeve, Zander Aycock, Eduardo Marconi Pinheiro Lima, Linda Bustos, Marouscha Dorenbos, Cristina Molina, Tim Donets, Jarrah Hemmant, Cristina Giorgetti, Tom van den Berg, Tyler Hudson, Oliver West, Brian Poe, Carlos Trujillo, Eddie Aguilar, Matt Tilling, Jake Sapirstein, Nils Stotz, Hannah Davis, Jon Crowder, Mike Fawcett, Greg Wendel, Sadie Neve, Cristina McGuire, Richard Joe, Ruud van der Veer, Merritt Aho, Felipe Henrique Fogarolli, Riccardo Oricchio, Bruno Borges, Daniel Mullins, and Matthew Bass.