Continuous Integration (CI) systems automate the building, testing, and possibly more. However, it is still unclear how CI should be implemented in different contexts. Therefore, this paper tries to answer the question "What metrics can be used to describe project activity", as part of a bigger study. We mined information from 500 repositories and then applied several analysis techniques to find out whether a metric can be used to describe activity or not. Among the results, we show that the activity around a release date increases, and that Java is a way more active language than other languages, with the highest amount of commits, closed pull requests, contributors, issues, and releases.