Resource Assignment vs Work Input Sequence

[peter.weinstein]

Hello;

I am a software developer and I use Microsoft Project 2003 to estimate the
duration of a task given the work that is required and the availability of
resources. At the start of a project I determine the tasks that need to be
performed, the work that is required and the availability of resources (if
possible).

I have configured Project so that my tasks are Fixed Work. In the past I
have first input the amount of work that is required to perform the task and
second assigned a resource to the task. What I recently discovered is that
Project will adjust the availability of a resource when I follow this
sequence. This is an unwanted result and yields an estimated duration that
is greater than expected. However, if I change the sequence so that I first
assign a resource to a task and second input the amount of work that is
required, Project will accept the availability that I have assigned for the
resource and will estimate the duration correctly.

It is more natural for me to first input the work and second assign the
resource. Is it possible to configure Project so that I can proceed in this
manner while preventing any change to resource availability once the resource
is assigned? I believe that this would then yield an accurate estimated
duration. This would be beneficial because sometimes the resource is not
known (or their availability) when the work is initially input.

If I have to change the sequence, can you explain why Project requires that
I first assign the resource and second input the work? Also, if I later have
to adjust the availability of a resource or swap resources will Project
continue to provide an accurate estimated duration?

Thank you for your help.

 

[JulieS]

Hi Peter,

I think some of the variation you are seeing is rooted in what Project
will calculate based upon what pieces of information you supply to the
task on resource assignment.

In Project Work, Duration, and Assignment Units are related
mathematically through the formula:

Duration = Work * assignment units.

Depending upon which variable or variables you supply, Project will
calculate the other.

For example:

Create a task and enter in 15 hours of work before assigning the
resource. Do not enter a value in the duration field, and Project will
put in the value of 1 day? (Default)

Then: assign the resource but do not specify assignment units.
Project assigns the resource at the maximum units specified in the
Resource sheet (100% default) and adjusts the duration of the task
following the formula:

Work/units = Duration
15 hours/100% units = 1.88 days duration
As you entered neither the duration, nor the assignment units, Project
assumed you wish to assign the resource at maximum units, and wanted
Project to calculate the duration of the task.

Create another task, with 15 hours of work but enter a 2 day duration.
Assign the resource and again do not specify units.

Project keeps both the Work (15 hours) and the duration (2 days) that
you entered and calculated the assignment units of the resource at 94%.
Again, Project assumed as you entered both work and duration that you
wanted to calculate the assignment units.

*However* , if you enter a combination of work and duration (too much
work for too short a duration), when you assign resources without
specifying units, Project again will assign at maximum and recalculate
duration, because otherwise, if the assignment units were calculated
based Duration/Work, the assignment units would be greater than maximum
units and the resource would be overallocated.

Once you have made an assignment of a resource to a task, if you then
start changing one of the variables (Work, Duration, or Units) Project
will re-calculate another one of the variables to keep the formula in
balance. Which other variable is recalculate is based upon Task type.

In a Fixed Work task:
If you change duration, Project will recalculate units.
If you change units, Project will recalculate duration.
If you change work, Project will recalculate duration.

In a Fixed Unit task:
If you change duration, Project will recalculate work.
If you change work, Project will recalculate duration.
If you change units, Project will recalculate duration.

In a Fixed Duration task:
If you change work, Project will recalculate units.
If you change units, Project will recalculate work.
If you change duration, project will recalculate work.

I don't know how you are entering Work, nor assigning resources, but a
view that I use almost exclusively for assignment of resources is the
Task Entry view. Split your screen (Window > Split) from the Gantt view
to show the Task Form at the bottom pane. In the Task Form, you can
see/manipulate duration, work, assignment units as well as task type in
one easy screen.
--
I hope this helps. Let us know how you get along.

Julie

Visit http://project.mvps.org/ for FAQs and more information about
Microsoft Project.

 

[peter.weinstein]

Julie, thank you for your response. You mentioned something that I think may
lead to the answer and I want to give you some additional detail to consider.

My tasks are fixed work, duration and work is entered in hours and my hours
per day is 7. When I create a new task work defaults to 0 hrs and duration
defaults to 7 hrs?.

Input work first - I set work to 3.5 hrs and then assign a resource with 75%
max. units. The results is that duration remains 7 hrs? while the resource
is assigned 50% units. This is undesirable since I want the resource to work
all of their available units on this task (75%).

Assign resource first - I assign a resource with 75% max. units and then set
work to 3.5 hours. The results is that duration becomes 4.67 hrs? and the
resource is assigned 75% units. This is desirable however, I have to assign
the resource first which may not be known at the time that I am ready to
assign work.

One workaround is to continue to input work first and then use the Assign
Resources dialog box to assign a resource, increasing the 50% units that
Project assigns by default before closing the dialog box. The problem with
this approach is that I have to be aware of the resource's max. units so that
I can increase the units to the maximum. As you know my preference is to
have Project assign the max units by default. Is this possible?

 

[JulieS]

Well, Peter, you have just shown me something that honestly, I have
never noticed before in Project :-O.

Prior to your detailed explanation, I would have said that Project
assigns resources at their maximum units if you leave duration at
default and specify work. Chances are I have never stumbled across this
as I usually do not document tasks that are of less than a full day of
work and usually I specify work at resource assignment.

But after testing in multiple scenarios, I agree, in the circumstance
where the work is less than a full day (7 hours in your project), when
assigning resources to either a fixed work or fixed unit task, Project
is calculating resource units instead of assigning at maximum units and
recalculating duration.

I'm afraid the only reliable work around I can come up with is this
suggestion. Instead of recording Work in the Work field, add a custom
number field and enter the work there. This will serve as your way of
capturing the work estimates before resources are assigned. You may
modify the duration if you would like but it sounds as if you rarely are
playing with duration. When you assign the resource, Project should
assign at max. units and calculate work. Then simply copy and paste the
data from the custom Number field, Project will keep resource units at
max. and recalculate duration.

Not a truly elegant solution, but I hope it works for you.
--
I hope this helps. Let us know how you get along.

Julie

Visit http://project.mvps.org/ for FAQs and more information about
Microsoft Project.

 

[St Dilbert]

Hi Peter,

following the steps you described with my installation behaves as
desired. I.e. put in work first, assign resource with units, press ok
(in the split view with task entry) and the duration changes to
two/thirds of the working day (with the question mark there indicating
it's still estimated work).

So maybe it's a version (service pack) issue? I'm using Project Prof
2003 SP2.
If you're using the same version, we might have to compare our option
settings in detail.

 

[peter.weinstein]

St Dilbert, thank you for the reply. I am running Project Prof 2003 SP2 as
well. Here are my Calendar Options

Week starts on: Sunday
Fiscal year start in: July
Default start time: 9:00 AM
Default end time: 5:00 PM
Hours per day: 7
Hours per week: 35
Days per month: 20

Here are my Schedule Options

Show scheduling messages: Checked
Show assignment units as a: Percentage
New tasks: Start On Project Start Date
Duration is entered in: Hours
Work is entered in: Hours
Default task type: Fixed Work
New tasks are effort driven: Disabled and Checked
Autolink inserted or moved tasks: Checked
Split in-progress tasks: Checked
Tasks will always honor their constraint dates: Checked
Show that tasks have estimated durations: Checked
New tasks have estimated duration: Checked

Here are my Calculation Options

Calculation Mode: Automatic
Calculate: All open projects
Updating task status updates resoure status: Checked
Move end of completed parts after status date back to status date: Unchecked
Move start of remaining parts before status date forward to status date:
Unchecked
Edits to total task % complete will be spread to the status date: Unchecked
Inserted projects are calculated like summary tasks: Checked
Actual costs are alsways calculated by Microsoft Office Project: Checked
Default fixed cost accrual: Prorated
Calculate multiple critical paths: Unchecked
Tasks are critical if slack is less than or equal to: 0 days

Also, my Standard (Project Calendar) weekday working time is Nondefault
working time with the hours

From: 9:00 AM
To: 12:00 PM
From 1:00 PM
To: 5:00 PM

Do the Options above match your own?

 

[St Dilbert]

ok - my mistake. In first trying to reproduce I always "assigned at
75%" instead of "assigning somebody with max 75% availability".

Sorry to report that now I can see the same behavior you do and I
haven't found a combination of options that changes it.

So apparently Project first spreads an assignment over a working day
calculating units necessary and only starts changing duration when
assigning at max units can't finish the work in one day. I tried
playing with the leveling options ("minute by minute" instead of "day
to day"; Word can change individual assignments and so on) but to no
avail.

This is a new discovery for me and I sifted through some of my older
plans -> apparently this has been happening to me all the time
unnecessarily stretching some of my plans out for a few fractions of
days.

This went unnoticed thus far because I rarely have assignments with
less than one day and I don't even try to optimize resource usage
within a day - in systems integration I'm happy to see the weekly
workload close enough to our contracted 38 hours. But I imagine in a
more precise environment like power plant maintenance this "feature" of
project would wreck my nerves. Right now I can't see any value in this,
especially since levelling will delay tasks before changing assignment
units.

hmmm.. so my projects that finished early were actually scheduled lazy
;-) ?

 

[Jan De Messemaeker]

Hi,

Just for the sake of precision, quote:
levelling will delay tasks before changing assignment

units.

Levelling DOES NOT, never ever, change assignment units. It only delays
assignments.
Hope this helps,