[jdreaver]

The book is a bit more foundational than that. It teaches you about Bayesian statistics, and discusses (among other things) why the concept of binary yes/no statistical significance is usually not the best way of evaluating a hypothesis with data.

However, for your question specifically, the choice of prior is less meaningful when you have lots of data, and presumably a web app seeing hundreds or thousands of requests per second can gather enough data to determine if the canary has a different latency profile than the deployed version within a few seconds. Also, presumably you would use an uninformed prior for a test like that. If I were trying to prevent latency regressions in an automated deployment pipeline I would just compare latency samples after 1 minute with a t-test or something simple like that.