In Microsoft Project you can specify Effort driven tasks. But how exactly does this effect your Microsoft Project schedule?
Effort driven calculations only apply after resources are initially assigned to a task. And it effects how the dependent variable in the work equation is calculated. The work equation is as follows:
Work = Duration x Units
To clarify this just a little, the term ‘Work’ in Microsoft Project is referring to the number of hours a labor resource will work on an activity. In the work equation you can choose any term as the constant, change either of the two remaining variables as the independent variable, and calculate the third term as the dependent variable. (Note that units in the work equation is the effort). This work equation also computes differently depending on whether your task is Effort driven or not.
Microsoft Project and Effort Driven Tasks
This article demonstrates how the Effort driven tasks setting affects work equation calculations in Microsoft Project.
In Figure 1 we have a schedule displaying tasks and all the differing duration type and Effort driven combinations.
There are five possible combinations, as the Fixed Work duration type is always Effort driven. Observe that each task is assigned a site foreman resource. (You may also observe that our tasks are all over allocated. This is because we have one site foreman resource available and scheduled to work on five different parallel tasks).
How does Microsoft Project behave in each scenario when we add an additional resource? To help us investigate, in Figure 2, we select details to display the resource assignments for each task.
We continue and highlight the site foreman resource, right click, and select Work from the popup menu, Figure 3.
Now that our views are set let’s proceed and examine the effect of the Effort drivensetting on each duration type.
Task A: Figure 4 displays the first task (task A) and its initial resource assignment.
The duration type is Fixed Units and Effort driven is no. In Figure 5 we assign an additional Common Laborer to task A.
This Common Laborer resource assignment adds another resource that has an 80-hour work unit. In this scenario the effort or units of each resource is constant. The total work is the dependent variable and doubles from 80-hours to 160-hours, Figure 6.
Task B: Figure 7 displays task B and its initial resource assignment.
The task B duration type is Fixed Units and Effort driven is yes. We proceed and assign the Common Laborer on task B. The schedule updates in Figure 8 by reducing the task duration to 5-days and setting the work unit of each resource to 40-hours.
So, if the assigned task type is Fixed Units and it is Effort driven, assigning additional resources shortens the task duration, decreases the work unit of each resource, but keeps the total work unchanged.
Task C: In task C, Figure 9, duration is fixed and Effort drivenno.
We assign the Common Laborer on Task C. This time the duration remains constant and the total work increases to 160-hours, Figure 10.
Task D: The task duration is fixed and Effort driven yes for task D, Figure 11.
When the Common Laborer is added to task D, Figure 12, the work unit of each resource becomes 40-hours or effectivity part-time efforts over the fixed ten day duration task. The total work is unchanged at 80-hours.
Task E: Figure 13, Task E is type Fixed Work and Effort driven yes.
Again, Effort driven is always yes for fixed work. When the Common Laborer is included the total work remains fixed at 80-hours, and the duration decreases to five days, Figure 14.
It is apparent that Effort driven tasks decrease task durations according to the respective effort.
Depending on your duration type and Effort driven setting, Microsoft Project adjusts the work unit of each resource and/or the duration of the task. When your task duration can shorten proportionately to the resource effort, use Effort driven. This holds true for both Fixed Units and fixed work duration types.