Managing Resources in Office Project
When you start assigning resources to tasks in Microsoft Office Project, the durations of the tasks automatically change. To understand why, you need to understand how Project allocates resources.
Project follows one formula for all internal resourcing calculations: Work = Duration × Resources. In other words, if two men take two hours to mow a lawn, one man will take four hours, or four men will take one hour, to mow the same lawn. Now you know why task durations constantly change if you add or remove the resources allocated to those tasks.
You can stop Project from recalculating time schedules in this way by configuring it to keep one parameter fixed and calculate just the others.
1. Open the task's properties.
2. On the Advanced tab, configure the task type as being Fixed Duration, Fixed Work, or Fixed Units (that is, resources). By changing this setting, you can tell Project what parameters in the equation should remain the same, no matter what changes you make to the task.