This article explains an often-overlooked effect that can distort metrics during feature roll-out. The primary audience are software engineers and managers working on infrastructure and libraries. I want to motivate this problem with a fictive scenario: Alex wrote a replacement for an old and inefficient component in their app. It took the team a few weeks to implement and they carefully measured on test devices that it improves all core metrics. It is faster, uses less memory, all the good stuff. Following procedure, Alex’s new code is bundled with the next release and they open it to 1% for an A/B test. ...

This article explains advanced A/B test concepts. The primary audience are engineers encountering such A/B tests for the first time. A/B tests allow engineers to validate fixes, test for regressions, and measure improvements. In most situations the standard approach is to create a control and a test group of equal size (e.g. both 5%). Users within the test population (e.g. 10%) are then randomly assigned to one of these. However, sometimes more intricate methods can improve the user experience and make deployment safer and more effective. ...

This article discusses how long-term survival rate of internal software projects can be improved. The primary audience are senior software engineers and engineering managers working in medium to large organizations. When searching for “maintainable software”, many articles ([1], [2], [3]) focus on good coding practices. And certainly, good naming conventions, readable code, continuous integration, unit testing, … are all very important. However, I feel that many discussions implicitly assume a caring person who is motivated and capable to take care of the required maintenance indefinitely. I found that this is often not the case. In a larger organization with considerable churn and regular changes in direction, it quickly happens that projects, which were once a great success, quickly fall between the cracks. ...

This article shares experiences with Python drawing libraries that I was missing when I started. The primary audience are software engineers who are looking for the tool for simple graphics. In 2020 the pandemic disrupted life. This included the cancellation of the traditional May Bumps rowing race that happens in Cambridge every year. Therefore, a group of rowing enthusiasts got together and organised a decentralized running event called Virtual May Bumps. It’s been a great success in bringing the community together (while being apart) and raising almost £6000 for charity. ...