Variance is now the core of a project management system called earned value management, which tracks the project by considering effort "earned" against a budget only after it has actually been performed. For software projects, the variance is a measurement in person-hours (or person-days, person-years, etc.) that shows the difference between the effort planned to date on the baseline and the effort completed on the actual schedule.
Variance defined. EVM (earned Value Managment) introduced.
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