Project management and process improvement are a critical part of software development in an organization, especially for large scale and long-lived software. Metrics can be used as one of the means to evaluate this process. However, traditional methods of measuring effort, for example, focusing on editing time and lines of code produced, do not reflect the true cost to the organization. The organization pays developers for their time, regardless of whether they are writing code or performing other activities. This paper describes an experimental approach to track and measure effort in developer days, using log files from a corporate repository. The data is fine-grained, empirical, and non-invasively collected. Results have been tested on several projects in a large organization over a period of many years.