比较的基准是：
1.as compared to where it was supposed to be
2. and where it was supposed to be going

EVM的特点或者好处：
EVM uses the
fundamental principle that patterns and trends in the past can be good predictors of
the future

原文：
1.1 THE ROLE OF EARNED VALUE MANAGEMENT
Feedback is critical to the success of any project. Timely and targeted feedback can
enable project managers to identify problems early and make adjustments that can
keep a project on time and on budget.
Earned Value Management (EVM) has proven itself to be one of the most effective
performance measurement and feedback tools for managing projects. It enables managers
to close the loop in the plan-do-check-act management cycle.
EVM has been called ‘‘management with the lights on’’ because it can help clearly
and objectively illuminate where a project is and where it is going—as compared to
where it was supposed to be and where it was supposed to be going. EVM uses the
fundamental principle that patterns and trends in the past can be good predictors of
the future.
EVM provides organizations with the methodology needed to integrate the management
of project scope, schedule, and cost. EVM can play a crucial role in answering
management questions that are critical to the success of every project, such as:
● Are we ahead of or behind schedule?
● How efficiently are we using our time?
● When is the project likely to be completed?
● Are we currently under or over our budget?
● How efficiently are we using our resources?
● What is the remaining work likely to cost?
● What is the entire project likely to cost?
● How much will we be under or over budget at the end?
If the application of EVM to a project reveals that the project is behind schedule
or over budget, the project manager can use the EVM methodology to help identify:
● Where problems are occurring
● Whether the problems are critical or not
● What it will take to get the project back on track.