The stability of software is a classical topic in software engineering. This research investigates stability of software architectures in terms of an object-oriented design principle presented by Robert C. Martin. The research approach is statistical: the design principle is evaluated with a time-series cross-sectional (TSCS) regression model. The empirical sample covers a release history from the Java library Vaadin. The empirical results establish that the design principle cannot be used to characterize the library. Besides delivering this negative empirical result, the research provides the necessary methodological background that is required to understand TSCS modeling.