Shifting resources, duration, or work within a schedule

Effort-driven scheduling automatically adjusts your schedule if you change a task's duration, the number of resources assigned to a task, or the amount of work a task requires. Effort-driven scheduling uses the following formula, with one of the factors fixed:

Work = Duration * Resources

In Schedule Manager, effort-driven scheduling is enabled for all tasks by default. You use the Fixed Type property of the task to control which of the three factors remains fixed and which change to accommodate changes to the schedule.

The Fixed Type property is set to Fixed Work by default. However, you can set the task type to be Fixed Resources or Fixed Duration instead.

Fixed Type behavior table

Fixed Type	When you change Resources, Schedule Manager changes	When you change Duration, Schedule Manager changes	When you change Work, Schedule Manager changes
Fixed Resources	Duration	Work	Duration
Fixed Duration	Work	Resources	Resources
Fixed Work	Duration	Resources	Duration

For example, if you add resources and the Fixed Type property is set to:

• Fixed Resources or Fixed Work — the duration decreases.
• Fixed Duration — the total work increases.

When you assign resources to a Fixed Duration task, Schedule Manager initially sets the work level for each resource to 100% for the entire duration of the task. However, you can adjust the work percentage level while assigning resources. If you add another resource, their work level is added to the total work, instead of reducing the work of the other resources.

Use Fixed Duration tasks when the duration should not change regardless of changes to the number of resources. For example, a project plan review task assigned to five reviewers for one week: if a manager is added as another reviewer, you do not want the amount of work reduced and you still want all reviewers to have one week. Setting Fixed Type to Fixed Duration keeps the previously assigned reviewers' time and work the same, and adds the new reviewer's work to the total work for the same duration.

For Fixed Resources or Fixed Work tasks, after the first time resources are assigned, any change in resources equally divides 100% of the work percentage among all assigned resources. The total work value does not change.

Constraints and dependencies interactions

If you applied constraints or dependencies to your task, Schedule Manager might prevent changes you want to make or ask you to remove the constraint:

• If a task has the Fixed constraint applied, you cannot make a change that changes either the task duration or the start and end dates. Attempting to add resources to a Fixed Work task with a Fixed constraint results in an error.
• If you attempt to change the start date of a dependent task with the As Soon As Possible constraint to start before its predecessor task, Schedule Manager warns you it violates the task constraint and asks if you want to remove the constraint and continue. If you remove the constraint, the start date is changed; if you keep the constraint, the task is moved back to its original start date.
• If you use Finish Date Scheduling, you adjust the finish date instead of the start date of the task, subject to constraints.

Note: Shifting resources, duration, and work totals may cause other parts of the schedule to change, especially if you have many tasks that have constraints and dependencies. After updating your tasks, be sure to review the entire schedule to note all the changes.

Note: When the Schedule Task has no resource assignment, the values for duration and work estimate are the same. When the Schedule Task has resource assignment with 0% load, the work estimate is the same as the duration.