This paper addresses a set of relevant issues in the context of the definition and application of measurement to long-term software evolution processes and their products. It presents a practical example using empirical data from one of the systems studied as part of the on-going FEAST (Feedback, Evolution And Software Technology) investigation. Such example demonstrates the use of a sequential statistical test (CUSUM) on a suite of eight evolution activity metrics. The metrics are based on module and sub-system counts. The test permitted examination of whether productivity had changed over an 11-year period. Results were consistent in six of the eight metrics studied, suggesting that sequential tests have potential in, for example, measuring the impact of process improvement (intervention analysis), identification of stages of software evolution and, in general, in supporting evolution management.