EVM
Earned Value Management (EVM) is a project management technique that allows for objective measurement of project progress. EVM uses predefined metrics to assign quantifiable value to accomplished work. This is called Earned Value (EV). The assessment of the value associated with future work is called Planned Value (PV). The basic requirement of any EVM system is that it quantifies progress on a project using PV and EV. EV is assessed by the summation of the completed PV from the start of the project to the current stage.
A math-friendly individual may find this elaboration helpful:
http://en.wikipedia.org/wiki/Earned_value_management