Schedule variance is a quantitative measure used by project management personnel to determine schedule performance during or after the completion of a project. It is calculated using a simple algebraic equation where the earned value (EV) represents the actual amount of time taken to either complete the project or progress to the project’s current stage. The planned value (PV) represents the amount of time which reaching the project’s current progress should have taken to achieve according to the project management’s schedule. Schedule variance (SV) is found by subtracting PV from EV. EV-PV=SV
Schedule variance and its exact number may indicate many possible things to project management. A number approaching zero would indicate that the scheduling and timeframes generated by project management were accurate within a small margin of error. A figure that is well into negative numbers would mean that either project management over estimated the amount of time needed or they overestimated the budget and workforce measured in raw man hours that would necessary to complete the project. This is not a good thing either as it represents an unnecessary expenditure of resources. A schedule variance figure high in positive numbers could represent many things. It could indicate that project management underestimated the amount of time needed to complete the project, or it might indicate that the budget and workforce was insufficient. It could also mean that project management or the workforce suffered setbacks, foreseen or otherwise, which may or may not have been avoidable.
This term is defined in the 3rd edition of the PMBOK but not in the 4th.