How I learnt to stop worrying and made the inbox-as-to-do-list approach work for me.

I know. I know. I know! Using my inbox as my to-do-list is considered bad practice, and I should feel bad for even trying.

Several well known time management books explicitly advise against this approach. Based on this advice, I have tried different tools and techniques to create a to-do-list separate from my inbox. Yet the honest truth is that all of these attempts didn’t work nearly as well for me as my current Gmail setup.

I learnt to stop worrying and made the inbox-as-to-do-list approach work for me. …

Mediation Analysis to Disentangle Direct and Indirect Effects

Written by: Tolga Oztan, Zoe van Havre, Chad A Davis and Lukas Vermeer.

At, one of the key ingredients to customer-centric product development isn’t just bright minds having great ideas, but collecting the evidence to support these ideas. We test each idea addressing a customer pain point via an A/B test using our in-house experiment platform. …

How we use online controlled experiments at to release new features faster and more safely

Written by Iskra and Lukas Vermeer.

At, experimentation is an important part of our product development cycle. On a daily basis we implement, deploy to production, execute and analyse hundreds of concurrent randomized controlled trials — also known as A/B tests — to quickly validate ideas. These controlled experiments run across all our products, from mobile apps and tools used by accommodation providers to customer service phone lines and internal systems.

Almost every product change is wrapped in a controlled experiment. From entire redesigns and infrastructure changes to the smallest bug fixes, these experiments allow us to develop and iterate on ideas safer and faster by helping us validate that our changes to the product have the expected impact on the user experience. …

Categorising Common Challenges

Written by Timo Kluck and Lukas Vermeer.

Online experimentation platforms abstract away many of the details of experimental design, and their users do not have to worry about sampling, randomisation, subject tracking, data collection, metric definition and interpretation of results. The rapid adoption of these platforms in the industry might in part be attributed to the ease-of-use these abstractions provide. However, there are common pitfalls to avoid when running controlled experiments on the web, and one needs experts familiar with the entire software stack to be involved in the process.

In this post, we argue that these pitfalls are not the result of shortcomings specific to existing platforms which might be solved by better platform design. Rather, they are a direct consequence of what is commonly referred to as “the law of leaky abstractions”. That is, it is an inherent feature of any software platform that details of its implementation leak to the surface, and that in certain situations, the platform’s consumers necessarily need to understand details of underlying systems in order to make proficient use of it. …


Lukas Vermeer

I help thousands of people run experiments to make better. I explain science using historical narratives and teach statistics through storytelling.

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