November 11, 2019

Planning A/B tests with a symmetric risk profile (α=β)

Here is a somewhat unconventional recommendation for the design of online experiments: Set your default parameters for alpha (α) and beta (β) to the same value. This implies that you incur equal cost from a false positive as from a false negative. I am not suggesting you necessarily use these parameters for every experiment you run, only that you set them as the default. As humans, we are inescapably influenced by default choices1, so it is worthwhile to pick a set of default risk parameters that most closely match the structure of our decision-making. Read more

July 17, 2016

Test your product assumptions with GA Intelligence Alerts

A good chunk of the job of being a PM or analyst involves spending time analyzing patterns of user behaviour, often to answer specific questions. Over time though, we build up mental models and heuristics which allow us to use our prior knowledge to answer questions more quickly. More knowledge is good, right? On one hand, past experience calibrates our sense of prior probability, which allows us to make better decisions in noisy contexts. Read more

February 12, 2016

Tracking: Organizational Challenges

There are plenty of technical guides online about tracking user behaviour using GTM. But I haven’t found as much about dealing with the organizational challenges that may arise when making changes to tracking. One of my main projects at Carmudi was improving our tracking. The key challenge was that I was not building tracking entirely from scratch. We already had a buggy tracking implementation that was feeding data into some of the most important reports in the organization. Read more

© Geoff Ruddock 2019