Durations and Assignments Change as Resources are Assigned in MS Project
Microsoft Project has some complex user definable relationships that determine which parameters change when resources are added to tasks. For example these relationships may result in durations or hours per resource reducing as resources are added to tasks.
This section will explain how resource assignments calculate and make some suggestions on how to set up the software so the tasks calculate the way you expect.
Task Type – Fixed Duration, Fixed Units, Fixed Work
Users must understand the relationship between the following parameters:
– The task Duration,
– The Work (the number of hours required to complete a task), and
– The Units per Time Period (the rate of doing the work or number of people working on the task).
The relationship is:
Duration x Units per Time Period = Work
For example, a 2-day task at 8 hours per day has a Duration of 2 x 8 =16 hours. If 2 people are assigned to the task the Units per Time Period is 2.00 or 200% and the work is 16 x 2 = 32 hours.
There are three Default task type: options and the default is assigned in the Tools, Options…, Schedule tab. Each new task is set with this Task Type. It may be changed at any time for each task in the Task Type field which may be accessed in a number of places such as the Task Type column the Task form, Task Details form and the Task Information form.
The Default task type decides how this relationship operates when one parameter changes. They are:
|Fixed Duration||The Duration stays constant when either the Units per Time Period or Work are changed.
A change to the Duration changes the Work.
|Fixed Units||The Units per Time Period stay constant when either the Duration or Work is changed.
A change to the Units per Time Period changes the Duration.
|Fixed Work||The Work stays constant if either Duration or Units per Time Period are changed.
A change to the Work changes the Duration.
Therefore your estimate will not change when you change Duration or Units per Time Period.