EVM Explained: Variance
“If you keep going at this speed, you’re going to be late!” That’s my simplistic real-life analogy of earned value management. It’s a simple bit of math that we all do in our heads anytime we’re trying to get somewhere or finish something. If you gave yourself an hour to get there and after a half-hour you’re still less than half-way, you’re going to be late. It’s that simple. As simple as it is, it requires us to know quite a bit of information about the current situation in order to calculate late vs. on-time. Just like EVM, you need to know 3 key elements to make the calculation: Your speed Remaining distance to go Remaining time left Cost Variance If you know those 3 values, you can not only calculate whether or not you’re going to be late, but you’ll also know how late. In earned value management, the “how late” answer would be called Variance. Whether we’re talking about time, cost or hours, variance is determined by knowing three things about your project: Your budget How much of that budget you’ve spent so far (actual) How much work has been completed (as a percent) To save you from having to read it here, you can have a look at this site to get the details on the math for calculating variance (and any other earned value metrics). Depending on your preference, variance can be expressed as a whole number or as a percent. Most people tend to speak about variance in percent terms since it gives you a sense of the magnitude. For example, “we’re 17% over budget.” It’s key to point out that that would be a


