EVM is a technique for showing how closely a project is following both its planned schedule and planned costs. It's a superior method to simply reporting time and cost variance, since if the project has slipped but also underspent you cannot tell from the simple variances the degree to which the underspend has caused the slippage. EVM's cost efficiency and schedule efficiency (nothing to do with efficiency by the way!) can tell you this.
However agile methods do not have a fixed scope during their lifecycle and this can make EVM reporting effectively meaningless. The paper explains a technique for using the substitutability of User Stories, estimated in points, for overcoming this problem. If this is relevant to your business environment, I hope you find it useful.
Agile EVM has continued to develop since this paper and you can find more details and further references in the Wikipedia entry here: Earned value management: Agile EVM.
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