# the addition and removal of resources

In the previous lesson, the initial resource assignments were made for our project. But we need to learn how to make adjustments to how those resources are used. It is important that you read every part of this lab carefully, if not twice. Working with Effort-Driven Scheduling How a task reacts to the addition and removal of resources is defined by the scheduling method and the task type settings. In MS Project, the default scheduling method is effort-driven scheduling. Effort-driven scheduling extends or shortens the duration of a task to accommodate changes to resources but doesn’t change the total work for the task.

Work is the amount of effort, or number of hours, resources put into a task. The total work for a task is determined by the duration estimate for the task and the initial resource assignment using the following formula: Work = Duration * Units For example, say you give a task the duration of one day (or eight hours based upon a normal working day). If the initial resource assignment is two units (200%) of a particular resource, the total work for the task will be 16 hours. 16 hours = 1 Day (8 hours) * 200%

As resources are added or removed after the initial assignment, the amount of work is not recalculated, but redistributed among the resources. In other words, the duration is recalculated, not the work: Duration = Work / Units So if you assign two more units of the previous resource or two different resources, the total work remains 16 hours; however, the 16 hours is now redistributed among the four resources (16 hours divided by 4 units equals 4 hours of work per resource). The duration is now . 5 days (4 hours). .5 Day (4 hours) = 16 hours / 400%

Effort-driven scheduling assumes that the more (or fewer) resources you assign to a task will decrease (or increase) the duration of a task. “If I can use more people, I can get done faster”. The key to effort-driven scheduling is when you make that first assignment (when you press assign or press enter when entering resource assignments), that is when the amount of work is calculated and never changes when you make additional assignments or subtract resources. This effect is very important to understand! Let’s demonstrate this effect. 1. Log onto Windows. 2.

Open your completed file MyLab2_XXX. mpp. (or use the MyLab2_XXX. mpp file from Doc Sharing) Check the addendum at the end of this lesson to make sure your beginning file is correct. 3. Save as MyLab3_XXX. mpp, where XXX are your initials. 4. Make sure you are in Gantt chart view and your table is the task entry table. 5. From the View tab and the Task Views group, click Other Views and then More Views. 6. The More Views dialog box appears (figure 1). Select Task Entry and then press Apply. Figure 1 7. You will notice that your screen “splits” into two separate windows or panes again. 8.

The top window or pane is your Gantt chart view with the entry table. The bottom pane is known as the task form window and contains many different formats. The default format you are looking at is known as the resources and predecessors detail view. We will use different detail formats in this window in coming labs. For now, remember this is the task form window. 9. In the top pane, click on task #3, Inventory Current Equipment. Notice in the lower pane, the resource assignment you made from the previous lab, Systems Administrator. Remember that you initially assigned two units of this resource.

The duration you gave this task was 3 days (or 24 hours). When you made the assignment, the initial scheduling then calculated the work. Given the formula, work equals duration times units, 24 hours times 2 units equals 48 hours of work and that is what is in the work column for that resource. 10. Also notice the box Effort driven (next to the Previous button) is checked. That means that this task is using effort-driven scheduling. Also notice the textbox below it labeled Task Type and the phrase Fixed Units. We will be returning to this box shortly. 11.

Again, making sure you have clicked on task #3, open the Assign Resources dialog box from the Resource tab (the one with the faces). 12. Change the number of units of the resource Systems Administrator to 300%. (Either type in 300 or use the up arrow and then press enter). (Figure 2). Figure 2 13. Notice in the lower pane the units of the resource changed to 300% and the work remained at 48 hours, but notice the duration of the task: it changed to 2 days. Why? Taking our formula that work equals duration times units, when we make any change after the initial calculation of work, work is not recalculated, but the duration is!

Therefore (using our algebraic knowledge), duration is equal to work divided by units, or 48 hours divided by 3 units equals 16 hours or 2 days. Got it? Also remember the 48 hours is the cumulative amount of work for the three units. 14. But what happens if we now subtract some of the units? In your Assign Resources dialog box, change the units of Systems Administrator to 100%. What happened? Your work is still 48 hours, but since there is only one resource the duration is recalculated for 6 days (48 hours divided by 1 unit equals 48 hours or 6 days). 15. Change the units of resource for Systems Administrator back to the original 200%.

Your duration should return to the original 3 days. 16. Since this was the same resource, what would happen if we added a different resource? 17. Click on Systems Analyst and make an assignment of 100%. (Click Assign button or Press Enter). 18. You should now see in the task form the name of Systems Analyst appear and in the work column the 48 hours of work is now distributed evenly among the three resources (2 Systems Administrators and one Systems Analyst), but it still totals 48 hours. The duration is now 2 days, because each unit will be working 16 hours or 2 days. 19.

Notice the work stayed at 28 hours (in other words, work was not recalculated), but the duration changed to 3. 5 days! We would have expected that work should have been recalculated to 56 hours and the duration to stay the same. 11. Keep this assignment. The task type setting also has an effect on how tasks are scheduled. There are three task types: Fixed Units, Fixed Duration and Fixed Work. Using one of these types, any variable in the standard equation of Work = Duration * Units can be controlled. When Fixed Units task type is used (and it is the default), the duration of the task is affected.

Actually, fixed units sounds like a bad term for this task type. But if you notice from the table, the key is really effort driven. If a task is effort-driven, the philosophy says that the more resources, regardless of being the same resource or a different resource, work remains the same, but the duration will be affected. If a task is not effort-driven, but a fixed unit or resource-driven task, duration will only be affected if you add or subtract the number of units of the same resource! But what if you want to ensure that the duration of a task never changes?

You can control that by changing the task type to Fixed Duration. Let’s see that effect: 1. Keep the assignment you just made on Task #7 (100% of Systems Analyst), and now click on task #9, Issue RFPs. The resource assignment is the Project Manager. The duration is 7 days therefore work has been calculated as 56 hours of work based upon 1 unit (100%). 2. In the task form in the bottom pane, change the task type to fixed duration by choosing from the pull-down men, and check the effort-driven box). (Figure 4) Figure 4 3. Press OK to effect the change. 4.

Add the Financial Officer (100%) to this task and press the OK button. What happened? Figure 5 The Project Manager and Financial Officer are both assigned 28 hours worth of work over 7 days. If a task has the task type Fixed Duration, the duration of the task remains the same (fixed) when resources are added or removed; however work for each resource could be allocated differently depending on whether it is the same resource or a different resource. Here is a chart of how effort-driven scheduling could affect the workload of a resource (but not the task duration) when designating a task type of Fixed Duration:

Example: Task X has a duration of 2 weeks, and initial resource assignment of one unit of Resource A, and therefore an initial total work of 80 hours. | Fixed Duration With Effort Driven| Duration| Units| Work| Add one unit of same resource (A)| 2 weeks| 200% of Resource A| 80 hours each 160 hours total| Add one unit of different resource (B)| 2 weeks| 50% of Resource A 50% of Resource B| 40 hours 40 hours 80 hours total| Fixed Duration Without Effort Driven| Duration| Units| Work| Add one unit of same resource (A)| 2 weeks| 200% of Resource A| 80 hours each 160 hours total|

Add one unit of different resource (B)| 2 weeks| 100% of Resource A 100% of Resource B| 80 hours 80 hours 160 hours total| Let’s try this table to see if we can predict the effect of our scheduling: 1. Make sure task #9 (Issue RFPs) is selected in the upper pane. 2. In the lower pane, Select the Financial Officer and press the delete key to remove the Financial Officer. Press OK. 3. The task form should show the Project Manager back to 100% assignment and 56 hours of work. 4. In the task form, uncheck the effort-driven box and press OK. 5. Making sure you are still on task #9 again.

Add the Financial Officer and assign him back to the task (100%). What happened? 6. According to the above chart, if effort-driven is turned off and the task type is Fixed Duration, adding one unit of a different resource will not change the duration (it is still 7 days), but each resource will be assigned the same amount of work, 56 hours. (Keep this assignment as is). The last task type is Fixed Work. Fixed work means the total work for the task will remain the same when resources are added or subtracted. Only the duration and units are affected in a Fixed Work type task, but inversely.

If your Task Type is…| | Duration| Units| Work| | | Fixed Duration| Work| Work| Units| | | Fixed Units| Work| Duration| Duration| | | Fixed Work| Units| Duration| Duration| | Perhaps the best advice is the following: 1. Leave all tasks as effort-driven, fixed units unless the duration absolutely needs to remain fixed. Fixed durations are rare. Tasks such as waiting 1 hour after swimming may seem like a fixed duration, but can be best handled by using lag times. (Actually the above is really not a task). A better example of a fixed duration task would be driving a truck.