Earned value calculations can be done at various points during a project, but the numbers tend to stabilize when you're about 20 percent through, says Quentin W. Fleming, co-author of Earned Value Project Management (Project Management Institute, 2006) and a management instructor at the University of California, Irvine.

"So the point is, if you're 20 percent through the project, you can predict what the final costs are going to be, plus or minus 10 percent," Fleming says. "It's a very powerful tool, and here's what's powerful: If you're 20 percent through a project and you've been authorized $1 million, and your cost efficiency to date suggests you're going to need $2 million to finish the project, then management has decisions [to make]."

Despite EVM's reputation for offering insight into project progress, many IT executives aren't yet embracing the discipline, partly because the underpinnings that make it work aren't in place.

"The concept of earned value is really elementary project management. But the problem with many IT organizations is that they don't use rigorous project management methodology," says Dan Gingras, a partner in the information technology leadership practice at Tatum LLC, a consulting firm in Atlanta.

"In order to do earned value management, you have to have a good budget," he says. "In order to have a good budget, you have to back up one step further and follow a good project management methodology."