The estimate to completion or the ETC is an estimate of the additional money that will be necessary to complete the project. It is calculated from the estimate at completion that we discussed previously.
ETC = EAC – ACWP
Can you get into trouble with estimates at completion? You bet you can. As we have seen in the discussion of the EAC, there are many ways that this estimate can be made. The most common form is the budget at completion divided by the cost performance index. This is only a rough estimate of what the project will cost when it is completed.
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Using the estimate at completion predicts that the project will overrun or underrun its budget at the end of the project. While it is a good thing to keep the stakeholders and the managers of your company informed that projects are in trouble, it is a weak support for asking that the project be given additional budget. A good project manager who wants to keep his job will take the EAC and use it as additional supporting information to show that the project budget was originally overor understated. In addition to the EAC, the project manager should have much supporting information as to why the project is in the condition that it is in.