Change the task type for more accurate scheduling

You just assigned a few people to a task, and the task duration got longer, not shorter as you expected. Or maybe the reverse happened. Either way, you're stumped. Some tasks, such as curing cement, take a fixed amount of time no matter how workers are assigned to pouring the cement. Others, like building roads or software, grow or shrink in their durations, depending on the people and resources applied to them.

• To change the task types to better reflect these realities, double-click the task, click Advanced, and change the task type.

Tip: To speed things up, add the Task Type column to a sheet view. Right-click on a column heading and then click Insert Column.

Newer versionsOffice 2007

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Look closer into task types

• How task types change your schedule

• A real-world example of controlling the timing of tasks

How task types change your schedule

Project uses a scheduling formula that relates the three values of work, duration, and assignment units:

Work = Duration x Units

Setting a task's type allows you to "fix" (or make unchangeable) one of these values. Fixing one of the values places a priority on that value by telling Project not to change it when the other two values change. This applies to both automatically and manually scheduled tasks.

Here's a handy table to help keep all the moving parts of the scheduling formula in mind.

In a	If you revise units	If you revise duration	If you revise work
Fixed units task	Duration is recalculated.	Work is recalculated.	Duration is recalculated.
Fixed work task	Duration is recalculated.	Units are recalculated.	Duration is recalculated.
Fixed duration task	Work is recalculated.	Work is recalculated.	Units are recalculated.

Let's look at the three task types more closely. Fixing one of these values gives you powerful control over your schedule. But before you read on, make sure you understand the difference between the three pillars of Project scheduling: work, duration, and units and how they relate to each other. For a quick refresher read How Project schedules tasks: Behind the scenes.

People stumble over this all the time, so don't be discouraged if you don't get it right away. Mastering it will help grow your expertise as a project manager once you understand how to control task durations with task types.

The table below summarizes the task type and the impact on the schedule.

Task type	Impact on schedule
Fixed units	This setting assumes the number of people assigned to the task (units) is known and you don't want it to change, even if duration changes. When the work changes on a task, the duration changes, but not the number of people. This task types reflects most task realities in any project. Example: You have one person assigned to write a report that should take only two hours to write. If you decide that the reality of work on this report is that the two hours needs to be spread over two days on the calendar, you can change the duration to two days—without changing the number of people assigned to write the report. After all, you probably don't want more than two people writing the report anyway. In other words, you want the number of units (the one person) to stay the same. Note: This is the setting Project typically places on tasks. To change this default setting, click File > Options > Schedule, then select a different task type in the Default Task Type list.
Fixed work	This setting assumes work doesn't change, even after changing durations or adding people. Use this setting if you want to control the duration of tasks by adding or removing people. Example: It takes 300 hours to design a large garden as part of a housing project. And you want the garden built as soon as possible, so you start assigning more gardeners to the job (task). The duration of the garden task will decrease as you add more people. Note: You can't change the Effort driven setting for a fixed-work task. Project doesn't consider fixed work tasks to have flexible work values and are therefore always effort-driven. You can change the effort driven setting for task types.
Fixed duration	This setting assumes duration doesn't change, even when more people are assigned to the task. Use this setting if you have a duration in mind for a task before you know other information about the task. Example   : A weekly status meeting might take an hour. Set this task to fixed-duration, otherwise as you assign people to the task, the duration of the meeting will decrease. And we all know, adding people to meetings isn't likely to decrease their length (it could even make them longer!)

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A real-world example of controlling the timing of tasks

The following three scenarios demonstrate the ripple effect (and thus control) that task types have over the timing of tasks throughout the schedule.

Scenario one: Changing task type to fixed-units

Let's say you have a fixed-units task, with 1 full-time person available for 8 hours a day. Further, you've set the task up with a 10-day duration and 80 hours of work.

What you change	What Project does
Add a full-time resource	Project recalculates the task's duration. The task now has 2 units assigned, with a 5-day duration and 80 hours of work.
Increase the duration	If you have 8 days to complete the task rather than 10, Project recalculates the task's work. The task now has an 8-day duration, with 64 hours of work, and 1 resource unit.
Change the work	If the task will take 20 hours of additional work, Project recalculates the task's duration. The task now has 100 hours of work, with a duration of 12.5 days, and 1 resource unit.

Scenario two: Changing task type to fixed-work

Now you make the same task a fixed-work task. This means that the task can take only the amount of work you specify: no more, no less. Remember, the task has 1 full-time person available for 8 hours a day, and it has a 10-day duration with 80 hours of work.

What you change	What Project does
Add a full-time resource	Project recalculates the task's duration. The task now has 2 units assigned, with a 5-day duration and 80 hours of work.
Increase the duration	If you have 8 days to complete the task rather than 10, Project recalculates the task's resource units. In order to get the task done in 80 hours over 8 days, 1.25 resource units must be assigned. The resource unit that is currently assigned to the task is over allocated at 125%. You need to assign another person to account for the additional 25% allocation.
Change the work	If the task will take 20 hours of additional work, Project recalculates the task's duration. The task now has 100 hours of work, with a duration of 12.5 days and 1 resource unit.

Scenario 3: Changing task type to fixed-duration

Finally, let's say you make the same task a fixed-duration task. This means that the task must be completed in the duration you specify. Again, the task has 1 full-time person available for 8 hours a day, and it has a 10-day duration with 80 hours of work.

What you change	What Project does
Add a full-time resource	Project recalculates the work assigned to each resource. When just 1 person was assigned to the task, that resource had 80 hours of work to complete. When you assign another person to the task, each resource has 40 hours of work to complete over the same 10-day duration, for a total of 80 hours of work. By adding another resource unit, you also revise the allocation of both units to 50%, making them both available to work 50% on other tasks.
Increase the duration	If you have 8 days to complete the task rather than 10, Project recalculates the task's work. The task now has an 8-day duration, with 64 hours of work, and 1 resource unit.
Change the work	If, the task will take 20 hours of additional work, Project recalculates the task's resource units, so that the additional work can still be completed within the 10-day duration. The task now has 100 hours of work, with a duration of 10 days and 1.25 resource units. The resource unit that is currently assigned to the task is over allocated at 125%. You need to assign another person to the task to account for the additional 25% allocation.

Note: Because assignments of cost resources don't have values for work or units, these values will not be recalculated when the task's start date or finish date is modified. Dates are also never recalculated for a cost resource assignment, because you can't modify the work or units.

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These instructions are specific to Microsoft Project 2007.

Look closer into task types

• Overview of task types

• Remove effort-driven scheduling from your tasks

• Change the task type

Overview of task types

The three task types used in Project are fixed units, fixed work, and fixed duration. Project uses fixed units by default.

Each of the task types affects scheduling when you edit one of the three elements as follows.

In a	If you revise units	If you revise duration	If you revise work
Fixed units task	Duration is recalculated.	Work is recalculated.	Duration is recalculated.
Fixed work task	Duration is recalculated.	Units are recalculated.	Duration is recalculated.
Fixed duration task	Work is recalculated.	Work is recalculated.	Units are recalculated.

Examples of how the task types change the numeric values

Let's say you have a fixed-units task, with 1 full-time resource unit available for 8 hours each day. You set the task up with a 10-day duration and 80 hours of work.

• If you find out that another full-time resource can assist on the task, Project recalculates the task's duration. The task now has two units assigned, with a 5-day duration and 80 hours of work.

• If you find out that you have 8 days to complete the task rather than 10, Project recalculates the task's work. The task now has an 8-day duration, with 64 hours of work and 1 resource unit.

• If you find out that the task will take 20 hours of additional work, Project recalculates the task's duration. The task now has 100 hours of work, with a duration of 12.5 days and 1 resource unit.

Now let's say you make the same task a fixed-work task. This means that the task can take only the amount of work that you specify: no more, no less. In this example, the task has 1 full-time resource available for 8 hours each day, and it has a 10-day duration with 80 hours of work.

• If you find out that another full-time resource can assist on the task, Project recalculates the task's duration. The task now has 2 units assigned, with a 5-day duration and 80 hours of work.

• If you find out that you have 8 days to complete the task rather than 10, Project recalculates the task's resource units. In order to get the task done in 80 hours over 8 days, 1.25 resource units must be assigned. The resource unit that is currently assigned to the task is allocated at 125%. You need to assign another resource to account for the additional 25% allocation.

• If you find out that the task will take 20 hours of additional work, Project recalculates the task's duration. The task now has 100 hours of work, with a duration of 12.5 days and 1 resource unit.

Finally, let's say you make the same task a fixed-duration task. This means that the task must be completed in the duration that you specify. Again, in this example, the task has 1 full-time resource available for 8 hours each day, and it has a 10-day duration with 80 hours of work.

• If you find out that another resource can assist on the task, Project recalculates the work assigned to each resource. When just 1 resource was assigned to the task, that resource had 80 hours of work to complete. When you assign another resource to the task, each resource has 40 hours of work to complete over the same 10-day duration, for a total of 80 hours of work. By adding another resource unit, you also revise the allocation of both units to 50% each, making them both available to work 50% on other tasks.

• If you find out that you have 8 days to complete the task rather than 10, Project recalculates the task's work. The task now has an 8-day duration, with 64 hours of work and 1 resource unit.

• If you find out that the task will take 20 hours of additional work, Project recalculates the task's resource units, so that the additional work can still be completed within the 10-day duration. The task now has 100 hours of work, with a duration of 10 days and 1.25 resource units. The resource unit that is currently assigned to the task is allocated at 125%. You need to assign another resource to account for the additional 25% allocation.

Note: Because assignments of cost resources don't have values for work or units, these values will not be recalculated when the task's start date or finish date is modified. Dates also are never recalculated for a cost resource assignment, because you cannot modify the work or units.

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Remove effort-driven scheduling from your tasks

For all tasks, after you assign a resource, the task is scheduled according to the formula Duration = Work / Units. For any task, you can choose which piece of the equation Project calculates by setting the task type. When you assign or remove people from a task, Project lengthens or shortens the duration of the task based on the number of resources that are assigned to it, but Project does not change the total work for the task. This is called effort-driven scheduling and is the default that Project uses when you assign resources to tasks.

Although effort-driven scheduling can work in most scenarios, you may want to change this behavior to more accurately reflect what happens on a particular task when resources are added or removed. For example, you may want to see the total work increase as you add more people to a particular task.

Note: You cannot remove effort-driven scheduling from fixed work tasks. Fixed work tasks do not have flexible work values, and are therefore always effort-driven.

1. On the View menu, click Gantt Chart.

2. Click the row for the task that you do not want to use effort-driven scheduling.

   To change up to 10 tasks at once, hold down CTRL and click the row for each task. If the tasks appear next to each other in the grid, click the first task and then hold down SHIFT and click the last task to select the entire block of tasks.

3. Click Task Information , and then click the Advanced tab.

4. Clear the Effort driven check box.

When you work with effort-driven scheduling, keep the following in mind:

• The effort-driven calculations apply only after the first resources are initially assigned to the task. After the first resources are assigned, the work value doesn't change as new resources are assigned to or removed from the same task.

• If the assigned task type is Fixed Units, assigning additional resources shortens the duration of the task.

• If the assigned task type is Fixed Duration, assigning additional resources decreases the individual unit values for resources.

• If the assigned task type is Fixed Work, assigning additional resources shortens the duration of the task.

• Summary tasks and inserted projects cannot be set to Effort driven.

Change the task type

1. On the View menu, click Gantt Chart.

2. Click the task that you are changing.

3. Click Task Information , and then click the Advanced tab.

4. In the Task type list, click the task type that you want to change.

   Notes: 

   • If you click Fixed Work in the Task type list, you cannot change the Effort driven setting for the task. Fixed work tasks do not have flexible work values and are therefore always effort-driven.

   • You can view and change the task type for each task directly in your view by inserting the Type field. Click the column to the right of where you want to insert the new column, click the Insert menu, and then click Column. In the Field name list, click Type.

   • If you want to change the hierarchical structure of a task or subtask as part of an outline structure for your project, you need to indent or outdent the task rather than change the task type.

   • If you want to impose restrictions on the way Project calculates the start and finish dates of tasks, you need to set a task constraint, rather than the task type.

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