Changing Task Types
You might recall from Chapter 4, “Assigning Resources to Tasks,” that Project uses the following formula, called the scheduling formula, to calculate a task’s work value:
Work = Duration × Units
where Units refers to the resource assignment units, normally expressed as a percentage. Remember also that a task has work when it has at least one work (people or equipment) resource assigned to it. Each value in the scheduling formula corresponds to a task type. A task type determines which of the three scheduling formula values remains fixed if the other two values change.
The default task type is fixed units: when you change a task’s duration, Project recalculates work. Likewise, if you change a task’s work, Project recalculates the duration. In either case, the units value is unchanged. The two other task types are fixed duration and fixed work.
For a fixed-duration task, you can change the task’s units or work value, and Project will recalculate the other value. For a fixed-work task, you can change the task’s units or duration value, and Project will recalculate the other value. Note that you cannot turn off effort-driven scheduling for a fixed-work task.
Which is the right task type to apply to each of your tasks? It depends on how you want Project to schedule that task. The following table summarizes the effects of changing any value for any task type. You read it like a multiplication table.
To view the task type of the selected task, on the Standard toolbar, click the Task Information button. Then in the Task Information dialog box, click the Advanced tab. You can also view the task type in the Task Form. (When in the Gantt Chart view, you can display the Task Form by clicking the Split command on the Window menu.) You can change a task type at any time. Note that characterizing a task type as fixed does not mean that its duration, units, or work values are unchangeable. You can change any value for any task type.
In this exercise, you change scheduling formula values (work, duration, and units) and task types.
On the View menu, click Task Usage.
The Task Usage view appears.
On the Edit menu, click Go To.
In the ID box, type 2, and then click OK.
Project displays task 2, Review script, and its assignments.
The Task Usage view groups the assigned resources below each task and shows you, among other things, each task’s and assignment’s duration and work—two of the three variables of the scheduling formula.
Drag the vertical divider bar to the right so that the Start column is visible.
Next, you’ll add a column to the Task Usage view so you can see the assignment units—the third variable of the scheduling formula. You don’t need to modify this view every time you want to use it, but for our purposes here, this is a good way to illustrate the effect of changing task types on the three variables of the scheduling formula.
Click the Start column heading, and then on the Insert menu, click Column.
The Column Definition dialog box appears.
In the Field Name box, select Assignment Units, and then click OK.
Project inserts the Assignment Units column to the left of the Start column.
You can see that task 2 has a total work value of 32 hours (that is, 16 hours each for two resources), resource units of 100% each, and a duration of two days. Next, you will change the task’s duration to observe the effects on the other values.
After a discussion among all of the resources who will review the script, all agree that the task’s duration should double but that the work required to complete the task should remain the same.
In the Duration field for task 2, type 4d, and press F.
Project changes the duration of task 2 to four days and increases the work per resource to 32 hours each. Note the change highlighting applied to the Work and Duration values. You wanted the duration to double (it did) but the work to remain the same (it didn’t), so you will use the Smart Tag to adjust the results of the new task duration.
Point at the Duration field and then click the Smart Tag Actions button.
Smart Tag Actions
Review the options on the list that appears.
Because task 2’s task type is fixed units (the default task type), the Smart Tag’s default selection is to increase work as the duration increases. However, you’d like to keep the work value the same and decrease assignment units for the task’s new duration.
On the Smart Tag Actions list, click Resources will work fewer hours per day so that the task will take longer.
The assignment units value of each resource decreases to 50%, and the total work on the task remains unchanged at 32 hours (that is, 16 hours per each assigned resource).
Next, you will change a task type using the Task Information dialog box.
On the Edit menu, click Go To.
In the ID box, type 67, and then click OK.
Project displays task 67, Hold formal approval showing.
On the Standard toolbar, click Task Information.
The Task Information dialog box appears.
Click the Advanced tab if it is not already selected.
The selected task describes the formal screening of the film for the financial backers of the project. As you can see in the Task Type box, this task currently has a fixed-units task type.
The task is scheduled for a full day, although a few of the assigned resources will work for the equivalent of half a day. To reflect this (and properly manage resource costs for the task), you will make this a fixed-duration task and adjust the assignment unit values for some of the assigned resources.
In the Task Type box, select Fixed Duration.
Click the Resources tab.
In the Units column, set the units values for Mark Hassall and Scott Cooper to 50% each.
Click OK to close the Task Information dialog box.
The change highlighting shows you the updated work values of the two resources on the task in the Task Usage view. Note that the duration value remains unchanged.
On the View menu, click Gantt Chart.