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Understanding the Resource Assignment Fields
When you assign a resource to a task, you must at least identify the resource that is being assigned (in which case Project provides default values for the other essential assignment fields). You can
Figure 9.2. The task form displays all three key assignment fields in the resource details area.
Assigning a Resource
In practice, many organizations define the decimal format of assigning resources "FTEs" or Full Time Equivalents. When not rounded to a whole number, the assignment is
To choose the format for the resource units fields, choose Tools, Options and select the Schedule tab. In the Show Assignment Units as A field, select Decimal or Percentage. This setting affects the display for all work resources.
Material resources are always shown in decimal format, no matter which format you choose for work resources. For both work and material resource types, the Assignment Units field defines the number of resource units to be assigned to a particular task.
When the Assignment Units field for a programmer who is named Juanita is 100%, the assignment is a
However, when you assign a team of five programmers to a task, it's more intuitive to say that the units should be the decimal number 5 instead of the percentage 500%. It's even more difficult to understand the percentage format when you assign 25000% assembly-line workers (which is clearer as 250, in decimal format) or 1600% delivery trucks (that is, 16 delivery
The percentage format emphasizes the way Project uses the Assignment Units field. Project uses this field to calculate how many hours of work it will schedule for the resource per hour of working time on the calendar. For example, suppose you have a task that a team of two carpenters can finish in 4 hours. If you assign the two carpenters to the task, you expect 1 hour of work from each of them during every hour of time they
Thus, for work resources, Project uses the Units field as a
If the Assignment Units value is 100%, Project schedules 1 hour of work for every hour of working time on the calendar until the task is complete.
If the Assignment Units value is 200%, Project schedules 2 hours of work for every working hour on the calendar.
If the Assignment Units value is 25%, Project schedules work equal to 25% of the available time during each period on the calendar until the task is complete.
Note that when you assign 25% units of a resource to work on an 8-hour task (which is 2 hours of work during the 8 hours), Project schedules 15 minutes of work each hour. This would accurately portray the schedule for a chemist who needs to monitor an experiment for 15 minutes each hour. But in many other cases, the resource would probably do the 2 hours of work at one or two sittings. In this case, if you're not
For work resources, the default Units value for an assignment is
You can also assign a resource to a task with 0% units. In that case, Project calculates the work as zero and consequently calculates the cost of the work as zero also. For instance, you could assign zero units when you assign a contractor to a task and the contractor agrees to complete the task for a fixed fee. The amount of work is the responsibility of the contractor ”all you need to record is the fee, which you would enter in a cost field.
Note that if the only resource assigned to a task is assigned at 0%, Project makes the task a milestone. It is generally better to handle fixed-cost tasks like this example as described in "Assigning Fixed Costs and Fixed Contract Fees," p. 396.
You can enter fractions of a percentage in the Assignment Units field, but they display as rounded whole percentage
For material resources, the Units value is always formatted as a decimal. If you fail to enter the assigned units, Project
If you enter just a numeral (or a numeral with the material label) in the Units column for a material resource assignment, it is called a fixed consumption rate for the resource. The amount consumed is fixed and independent of the task duration. For example, to assign 4 yards of concrete to a task, you could type 4 or 4 yd ; either way, Project would respond with the value 4 Yd. If the task duration changes, this consumption rate does not change.
Note that if you type something Project doesn't understand, such as 4 yards when the material label is Yd, Project displays a warning that it is not a valid Units value (see Figure 9.3). The simplest method is to enter just the numeral and let Project provide the label.
You can assign material resource units that have a variable consumption rate , where the total amount consumed depends on the duration of the task. To create a variable consumption rate, simply enter the units, followed by a forward slash (/) and the abbreviation for the time period during which that many units would be consumed. For example 4/d or 4 Yd/d means 4 yards per day.
For example, suppose you are using a bulldozer on a task that consumes about 6 gallons of fuel per hour. You can define a material resource Diesel Fuel with the label Gal (for gallons). Then, you can assign the fuel to the task by entering 6/h or 6 gal/h in the Units field. For either entry, Project displays the equivalent, 6 Gal/hour, in the Units field. Project then calculates the total number of units consumed by multiplying this rate by the task duration.
A work resource spends hours of time or effort
Both the hours of work for work resources and the units consumed for material resource are displayed in the Work field. However, in calculating the total work for a task, Project ignores values for material resources and sums just the hours for the work resources.
For work resources, the
Work can be entered by the
If a work resource is scheduled full time (100%) on a task that has a duration of 1 week (40 hours), the resource is assigned to 40 hours of work (100% of 40 hours). However, if the resource is assigned to the task only half time (that is, Units is 50%), the resource is assigned only 20 hours of work. If two resource units work full-time (200%) all week, there are 80 hours of work. Other things being equal, the following hold true:
The longer the duration of the task, the more work is scheduled.
The larger the resource units assigned, the more work is scheduled.
The amount of work that Project schedules for the resource is tied to the duration of the task and the number of units assigned to the task. This relationship is defined more precisely in the section "Understanding the Work Formula," later in this chapter.
For material resources, the Work field shows the total number of physical units of the resource that are consumed in completing the task. If you enter the units, Project calculates the work units for you.
For fixed-rate consumption assignments, the Work field is the same as the Units field. If you assign 48 Gal of fuel, the Work field shows 48 Gal. If, however, you assign 48 Gal/d to a 10-day task, Project calculates the value 480 Gal for the Work field.
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