I got an interesting question last week regarding how to modify individual task assignments when more than one resource is assigned to a task, so I thought that I would share the answer here...
"When I enter the estimates for how long a project is going to take, I enter the duration for how long the task is going to take. Is it possible to enter a duration for each individual person? Say for example the duration for a task is 40 days, can I have one person only be assigned for 5 of those 40 days?"
The answer to this question requires that you understand the three task types within MSProject (Fixed Units, Fixed Work, and Fixed Duration) and how each type of task behaves when changes are made to the task. For those who would like to learn more about Task Types, please contact me or leave a comment on this post, and I would be more than happy to write about it.
Like many functions within MSProject, there are multiple ways to accomplish the same end result. Some people like to use menus to find the functions that they want, some people like to use toolbar buttons, and others like to use keyboard shortcuts.
In this instance, I'll accomplish the assignment manipulation by visiting the Task Usage view:
View > Task Usage
For the task in question, each individual resource assignment should be listed below the task. The Task Usage view allows me to manipulate several different aspects of each individual task assignment and see the results immediately.
Next, I'll make sure that the following columns are displayed in the view:
Work
Duration
Assignment Units
Type
If any of these fields are NOT displayed in the Task Usage view, I can insert them by using the Insert > Column menu command.
I’d like to point out that we CANNOT modify the Duration for each individual task assignment, as you can see if you try to enter a value for Duration on any of the assignment rows for a task. We can change the Duration for the overall task, but NOT for individual task assignments. Therefore, we'll need to utilize Task Types and modify the Work for the individual assignments.
For the task in question, locate the Type column in the Task Usage view, and set the value to Fixed Units. Referring back to the W=DxU equation…
Work = Duration x Units
...if we hold the Units value constant, then we change the Work value, then MSProject should recalculate the Duration value.
Going back to the original question above, let's build the equation (assuming Units = 1.0):
320 hrs (Work) = 40 days (Duration, at 8 hrs per day) x 1.0 (Units)
If we want to drop an individual assignment's Duration down from 40 days to 5 days, we'll change the Work value from 320 hrs to 40 hrs:
40 hrs (Work) = 5 days (Duration, at 8 hrs per day) x 1.0 (Units)
As a final example, let's assume that the Units value was 0.5, rather than 1.0, meaning that the resource is planning to spend only half of their workdays on the task:
160 hrs (Work) = 40 days (Duration, at 8 hrs per day) x 0.5 (Units)
What is the new Work value if we want this assignment to drop from 40 days down to 5 days?
? hrs (Work) = 5 days (Duration, at 8 hrs per day) x 0.5 (Units)
...changing the Duration units from days to hours for consistency throughout the equation…
? hrs (Work) = 40 hrs (Duration) x 0.5 (Units)
Work = 20 hrs
Therefore, to drop the Duration down to 5 days, we'll need to change the Task Type to Fixed Units, then change the Work value from 160 hours to 20 hours.
Good luck!