Invalid Schedule Margin

“If everything seems to be going well, you have obviously overlooked something.”

- Steven Wright

This metric only applies if schedule margin tasks are being used in the schedule. Otherwise, it can be ignored. If schedule margin tasks are being used, DCMA wants to ensure that they are being used properly.

What is a schedule margin task?

Schedule margin is a technique that allows for “wiggle room” to ensure that a milestone is completed on time. There are several ways to allow for this wiggle room, but one common technique is to insert a task as an immediate predecessor to the milestone that drives the milestone’s start date.

If this technique is being used, DCMA will check to make sure that the schedule margin task is being properly used as follows:

  • The duration should be set based on a risk management process.

  • The actual start date and actual finish date, if they are set, are the same. Since this task is simply a placeholder for risk events happening on other tasks, it should not be recorded with an actual duration greater than zero.

  • The successor should be a key milestone, contractual event, end item deliverable, or contract completion.

  • If the schedule margin task is recorded in the earned value management system, it should exist in the schedule as well.

When used properly, schedule margin tasks are good tools to ascertain the likelihood of a milestone being met on time. When used improperly, they can interfere with the forecast dates that are calculated in the schedule.

Next steps

If this check fails, it’s important to understand the underlying reason for the failure. Follow the above checklist to ensure that the schedule margin has been properly entered into the schedule.

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