When we changed the resources from 4000A 3000A for Task 3, Project didn’t calculate work. Instead, it changed duration. When you change the units assigned to a task, Project recalculates duration or work. To determine which of the two values should be recalculated. A task setting determines which value Project will change. The default setting for tasks is that they are effort-driven. With effort-driven tasks, the task’s duration is completely dependent on the resources you assign to the task.
If you add or remove resources after the initial assignment, Project will recalculate duration, but leave work alone:
• If you add resources, Project decreases duration.
• If you remove resources, Project increases duration.
Adjustments to duration when resources are added or removed are the result of effort driven scheduling. You can see how Project implements effort-driven scheduling if you assign a resource, and then add another resource to the same task. In Task 4, we’ll start by assigning one unit of resource. As with Task 1, Project calculates work at sixteen hours for the two-day duration:
In the normal course of events from this point forward, adding or subtracting resources affects only duration because the task’s default effort-driven setting forces Project to’ calculate duration rather than work. To see the recalculation in action, return to the Assign Resources dialog box and add another resource. Project adjusts duration: the two people now assigned c.an complete the 16 hours of work in 1 day rather than 2:
Effort-driven scheduling is the default because In many projects, the bulk of the tasks are effort-driven. Adding resources gets the task completed more quickly. If your project is composed mostly of tasks that are not effort-driven, you’ll want to change this default. To change the default for new tasks created in your project file, choose Tools Options to open the Options dialog box. On the Schedule tab, turn off the New Tasks are Effort Driven check box:
You’ll find out how to change the effort-driven setting for existing tasks in the next section.
Changing Task settings to Change the Way Project
Reva emulates Change in work, units, or duration always affects one of the other two variables of the assignment, For tasks created using the default task settings, after the initial assignment, Project recalculates duration rather than work and work rather than units. There’s only one problem with this recalculation paradigm, and at first glance, it’s a big one: this isn’t necessarily how you want Project to adjust the assignment (and ultimately the budget and schedule) when work, duration, or units change. For some tasks, adjusting duration or work isn’t appropriate.
As the project moves into development, you’ll do your job as a project manager by adjusting resources, work, and duration. These are typical project management tasks:
• Moving resources from a less-critical task to a more critical task
• Adding resources to complete a task more quickly
• Changing the amount of work required to complete a task satisfactorily, based on information from team members
• Adjusting the start or finish date for a task to keep the project on schedule Each time you edit one of the three variables in the assignment triangle, Project will recalculate one of the two remaining variables. To control which of the values is recalculated, you change the task’s task type and effort-driven settings.
There are three task fixed units, fixed work, and fixed duration-that determine which variables Project calculates when you’ assign resources. The variable you set as fixed is the variable Project will not change. The task type;’ combined with effort driven scheduling, determine the variables that Project recalculates when resources
are added or removed, or which units, work, or resource variables are edited.
By selecting a task type and effort-driven setting, you set Project’s calculation method for the selected task.
There are five unique task type/effort-driven combinations:
• fixed-unit, effort-driven (the default setting)
• fixed-work, effort-driven
• fixed-duration, effort-driven
Fixed means that Project won’t recalculate the field’s value when values change in either of the other variables. It doesn’t mean that the value can’t change: the project manager can and often will edit the value. Fixed-work tasks are effort-driven. If you select Fixed Work as the task type, Project automatically turns on the effort-driven setting and locks It so you can’t change it
Each combination is explained in detail in this section.
With a fixed-unit task, the first time you assign resources, Project calculates the amount of work that the resources can do by multiplying duration by units. After the initial assignment, Project holds units constant and adjusts duration when either work or units change. If the duration changes, Project recalculates work. As the project progresses, you’ll manage slipping fixed-unit tasks by increasing the units assigned to the task to accomplish the task more quickly .
Here is an example of a fixed-unit task. Refer to the previous list to see how Project would handle the task described in the example:
• You assign two gardeners to spend three days restoring the perennial gardens outside the new office building. If you add three more gardeners, more work will be completed in the same three days. If you assign the original two gardeners for six days rather than three, they’ll do twice as much work. If you tell the gardeners to do 100 hours of work, it will take them more than twice as long. For this type of task, change the task’s type to fixed unit, turn off effort-driven, and Project will recalculate work and duration, but will not recalculate units:
Fixed-Unit. Effort-Driven Tasks Project’s default task type is both fixed unit and effort driven. With effort-driven tasks, Project recalculates duration when you add or remove resources to a task. With fixed-unit tasks, Project doesn’t recalculate units.
With fixed unit, effort-driven tasks, then, there’s only one thing left to change=duration. Every change in units assigned or work required affects the schedule. You manage slipping fixed-unit, effort-driven tasks by adding resources to decrease duration.
With a fixed-unit effort given task:
you add or remove resource units, Project recalculates duration.
• If you change the percentage of a resource assignment, Project recalculates duration.
• If you change duration, Project recalculates work.
• If you change work, Project recalculates duration .
Here are examples of tasks that should have the default fixed-unit, effort-driven settings:
• Achievement specialists are assigned to evaluate children in a preschool.
Each evaluation takes an hour, and there are 240 children to evaluate. If you increase the number of specialists from 300% to 500%, the evaluations will be finished sooner. If you decrease the number of children that will be evaluated, duration should decrease.
• Your print shop accepts a large job that will take sixteen hours to print using cine offset press. If you assign two presses to the job, you want Project to recalculate duration because the task will be completed in half the time. If the customer doubles the amount of work, Project should double the duration. When you create a new task with Project’s default settings, it will be fixed-unit,
With fixed-work tasks, when you make the initial resource assignment, Project calculates the units of resource that are required to complete the task by dividing work by duration. By setting work and duration, you can calculate required resources easily. After the initial assignment, a change in duration affects units a change in units affects duration. (Project won’t, however, remove a resource assignment.) Fixed-work tasks are, by definition, effort driven Where you choose the Fixed Work task type, Project ruin’s the effort-driven check box on and.disables it:
You manage slipping fixed-work tasks by adding resources to complete the task more quickly. If you know how many days you have to finish the task, you can set duration and Project will calculate the resource % required. You see the difference between fixed-work tasks and the default task settings if you change the task’s duration. With fixed unit effort-driven tasks, a change in duration changes work. With fixed-work tasks, a change in duration changes units because Project won’t recalculate the amount of work.
The following tasks should have their task type set as fixed work:
• Your project includes a Write Scripts task that will take 40 hours. You assign a full-time programmer to work on the scripts for five days. If you add another full time programmer, the task will be completed in 2.S days. If you have your programmer work 12-hour days, the work will be done in 3.33 days. If you change the scope of the task and Increase work to S6 hours, it will take 7 days rather than S. If you change duration from 5 days to I, you’ll need 5OO%of a programmer to complete the task on time.
• You assign painters to prime the walls in an apartment building. The head of your paint crew says it would take 3 painters S days (120 hours of work). If you assign more painters, the job gets finished sooner. If painters work overtime, the job gets finished sooner. If you have to get the work done in 3 days, you can shorten the duration, and Project will calculate how many painters you need to assign.
If a task’s type is set to fixed duration, when you make the initial assignment, Project 2000 calculates work by multiplying units by duration. After the initial assignment, additional resources will complete more work during the duration, but duration is unaffected by resources or work. If fixed-duration tasks slip, there is no way to get them back on schedule a two-week fixed-duration task always takes two weeks. When fixed duration tasks are In the critical path and the project schedule is slipping, you manage the fixed task indirectly by adding, resources to its predecessors.
This task should be created as a fixed-duration task:
• This weekend, your local orchard will let you pick all the apples you want at a very low cost. If you take two friends with you, you can pick three times as many apples.
Conversely, if you need to pick three times as many apples as you can pick alone, you’d better invite a couple of your friends.
There is another reason to set a task’s type to fixed duration: a task’s duration is fixed, and the task is clearly not effort-driven. Examples include:
• A floor coating needs 72 hours to set.
• An eight-hour training takes a day. Adding a trainer won’t change the duration, but it will double the amount of “work” done during the day.
• A stakeholder has one week to review the proposed logo for a new product.
• The two-day retreat is scheduled as part of the project’s start-up.
• Any task being completed by someone outside the project team in a specified duration. You have one person assigned as liaison to the organization completing the task. You can’t directly control other resources assigned to the task. For your purposes, and the amount of work, other than that performed by your liaison,
Fixed-Duration, Effort-Driven Tasks With fixed-duration and effort-driven tasks, neither the duration nor the amount of work can increase, so adding resources means that each resource will be assigned at a lower percentage (they’ll spend less time working on the task), freeing them for other tasks. If you change the percentage of a unit’s assignment, Project recalculates work. You manage fixed-duration, effort-driven tasks by adjusting duration to get work done with fewer resources.