You are incorrect at what you assume should happen. A task has a duration
of 2 days (16 hours). If you assign a resource at 100% over 2 day of
duration he will accomplish 16 man-hours of work. But if you only assign
him at 50%, only half of the duration is converted into useful work and he
achieves 8 man-hours of work over the 2 day duration. WORK IS INDETERMINATE
UNTIL THE RESOURCE IS ASSIGNED AND ONLYTHEN DOES THE AMOUNT OF WORK
REPRESENTED BY THE INPUT DURATION BECOME KNOWN , calculated by project based
on the known duration and the units assigned for the resource. As I said
before, whatever your resource assignment percentage is, Project assumes you
knew thats what the resource's availability was when you came up with the
duration estimate in the first place. It doesn't change your 2-day duration
when you assign resource Bob at 50% because it's logic say "When Aren said
this task would take 2 days to do, he knew Bob was going to be assigned and
he knew that Bob was only available 50% so his input reads 'Task X is
defined as requiring whatever work it will take for Bob at 50% to finish the
task in 2 days'"
--
Steve House [Project MVP]
MS Project Trainer & Consultant
Visit
http://www.mvps.org/project/faqs.htm for the FAQs
(Grand summary: Project 2003 has a buggy/incorrect/defective way of
filling in the initial Work value for tasks 1. that did not previously
have a Work value and 2. for which a new assignment was made into a
blank assignment ("Resource Names") field where the assigned resource
has an availability other than 100%. The workarounds are cumbersome.)
The more I look at this, the more I am convinced that Project 2003 has
a major bug. Hereâ?Ts how you can reproduce the problem.
Create a blank, new project with tasks A-C with 2 hour durations. All
are first level tasks, so their WBS numbers are simply 1-3. All you
should have changed are the Task Name and Duration fields.
Create three resources: 1, 2, and 3. For each resource, double click,
go to General, go to the Units column of Resource Availability, and
type 75% for resource 2 and 50% for resource 3. (Resource 1 remains at
100%.)
Now go back to the task view. Assign resource 1 to task A, resource 2
to task B, and resource 3 to task C.
What SHOULD happen: since the Work field (which is hidden by default)
had no value previously, the Work field should take on the value of the
duration field, the duration should stay at 2 hours for task A, and it
should increase for tasks B and C.
What DOES happen: the durations stay the same, but the work goes to 16
hrs, 12 hrs, and 8 hrs, respectively.
Only in some weird alternate universe do work requirements drop when
your resources donâ?Tt have 100% availability. Since Project is
assuming the properties of a weird alternate universe and not of Earth,
I call this a big fat BUG.
Continue with the same project. Create tasks D, E, and F. "Unhide" the
Work column (right-click on Duration header and select Insert Column.)
Set each of these tasks with work of 2 days (Project will probably
auto-convert them to 16 hours. That is OK assuming an 8 hour workday.
This is adjusted through Toolsïf Optionsïf Calendar.)
Now assign resources 1, 2, and 3 to tasks D, E, and F, respectively.
Now what you find is that the Duration columns now have the correct
values, but they are followed by a question mark, suggesting this is
only a guess on Projectâ?Ts part. I understand the question mark to me
something along the lines of Project saying "be careful, Iâ?Tm just
making a guess and you need to double check this value because it could
bite you in the butt later if you leave it."
Now create tasks G, H, and I. Donâ?Tt change anything but their Task
Name fields. Assign resources 1, 2, and 3 to these tasks. Notice how
the Work field again changes.
WORKAROUND A:
Assign the same value to Duration and Work. This seems to make Project
function properly. However, it requires you to do double entry. Not
only is that bad design (on the software makerâ?Ts part), it could
potentially cause data concurrency issues.
WORKAROUND B:
Assign all resources as 100%, then later go back and change them to
their actual %. This is very cumbersome as there is no automated way to
change the percents after you assign the resources.
WHY THIS IS A PROBLEM:
No well-designed software should require double entry of everyday data
like duration/work. That is flat out bad design.
But there are other issues.
It is a perfectly acceptable project formulation model to (1) assemble
an organized list of tasks, (2) give each task a duration, and (3) and
assign resources to the tasks using resources that have a unit
availability other than 100%. Without employing a workaround, you end
up with screwed up Work fields for any tasks that were assigned a
resource with any availability other than 100%. I would love it if my
task durations could shorten when I am not fully available, but the
world doesnâ?Tt work that way.
By excluding the Work field from the default view, Microsoft clearly
did not intend for you to have to enter values in the Work field under
normal circumstances. In theory, you should enter a default work value
into the Duration field of new tasks (assuming that resource
availability is assumed to be "like" 100% until a resource is
assigned), then reasonably expect Duration to change if you later
assign a resource with availability other than 100%.
My view is further backed up by Microsoftâ?Ts own information at
http://tinyurl.com/elj33. If you change the units on a Fixed Units task
(the default setting) and you change the Units, then the Duration
should change, not the work.
Note that I agree 100% with the W=D*U equation. I am not challenging
that. My beef is that Work should be assumed to be the same as Duration
if Work has not previously been filled out. Because Microsoft is not
following that basic rule, assigning a resource that is anything other
than 100% availability causes erroneous data, forcing the planner to go
back and fix all the Work fields. Project planners don't have to fix
Work fields for 100% resources, and they shouldn't have to fix them for
resources other than 100%.
This whole problem can be fixed if when a resource is assigned, any
Work field which has been previously unassigned (or is 0?) takes on the
exact value of the Duration field. (Note: this is the ONLY automatic
modification to the work field that should happen under normal
circumstances for "Fixed Unit" tasks.) After that, the Duration field
may be adjusted based on the available Resource Units.
To resummarize: Project 2003 has a buggy/incorrect/defective way of
filling in the initial Work value for tasks 1. that did not previously
have a Work value and 2. for which a new assignment was made into a
blank assignment ("Resource Names") field where the assigned resource
has an availability other than 100%. The workarounds are cumbersome.
