Fixed Work Task

[JodyJ]

I have a task with the task type of fixed work. 2 resources assigned, 10hrs
each, 81% units, MS Project calculates duration of 3.09 days. If I increase
the units on both resources to 100%, the duration recalculates to 2.5 days,
"work" doesn't change. This is as I expected.

If I increase the duration to 5 days the units on one resource changes to
36% but the other remains the same. Why?

If I decrease the duration to 1 day, units on one resource changes to 125%
but units on the other resource changes to 0% and "work" changes to 10 hrs.
Why?

I thought with a "fixed work" task, "work" shouldn't change.

 

[jhalterm]

hello JodyJ,

I may not completely understand you but I will give it a shot. The reason
that the "units" change when you increase or decrease the duration is because
they are suddenly they have more or less time to do the work.

Example... If you were planting a garden and you knew it would take you 4
hours to do and you had all week (5 days) to do it then you might only spend
10% of your time planting the garden and the other 90% donig something else.
But what if all of a sudden you had only 2 days to plant that garden, well
now you will be doing the same amount of work (4 hours) but now you might
have to work 40% of the time to complete the task before the deadline. Same
goes if you had 2 weeks (10 days) to complete the task you might now only
spend 2% of each day working on planting the garden.

I'm not really sure why the other resource is not changing. I don't
understand that either so maybe someone can help you with that.

Hope this helps.

 

[Rod Gill]

Hi,

If you add two resources to a task then never edit either of their
assignments, changes to the task affect both assignments equally.

If you now add more work to one resource so its assignment finishes later
than the other, the task finish date is driven by the edited assignment.
Changes at the task level now only effect the edited assignment unless the
finish date gets to be earlier than the unedited assignment's finish date.

Select Window, Split
In the task form right click and select Resource Schedule

You can now look at the finish date of each assignment and experiment.

 

[JodyJ]

Your first statement is exactly what is NOT happening.....I noted "If I
increase the duration to 5 days the units on one resource changes to
36% but the other remains the same" I'm changing the tasks duration and
only one assignment is changing.

I also noted a situation where units are changing and I don't believe they
should ever change for a "fixed work" task.

 

[jhalterm]

JodyJ,

I agree with and am not sure why both resrouces are not updating. That
really is something I dont' get either.

The reason your units are changing when you change the duration of a task is
because you have fixed work selected. Change your type from fixed work to
fixed units before you change the duration and then the units will stay the
same. Then you will see the hours of work increase or decrease depending on
the direction you change the duration.

 

[Steve House [Project MVP]]

Fixed work does NOT mean woirk can never change - it's not an attibute of
the task but rather an attribute of editing the task. You have a task and
change its duration. If it's fixed work the units will change and if it's
fixed units the work will change. But even if it's fixed work I can freely
change the work to my heart's content, and then it will recalculate duration
in response.

You set a task type before making an edit to existing resources so that
Project will recalculate the one of the remaining two variables you intend
it to change and hold the other constant.

Why your's is behaving the way you say is hard to say but you do need to
realize that "fixed work" doesn't mean work can't change under any
circumstances.

 

[JodyJ]

Fixed work means the "work" field shouldn't change as a result of changing
some other field. This is exactly what is happening. I have a fixed work
task for which I lower the duration and "work" is changing.

 

[Steve House [Project MVP]]

That's what I meant by not understanding why your project is behaving the
way you say it is. Something else is going on that isn't apparent from what
you've given us in your posts.

One thing to mention - again, it may or may not be related to your issues -
but the relationship between work and duration is indeterminate prior to
assigning resources.

Something just occured to me - are you SURE that the task is really marked
"fixed work?" If *after* entering the task you tried to set it to fixed
work by pulling up the Tools Options menu and setting the default task type
on the Schedule tab to fixed work, that won't do it. Those settings only
affect tasks entered AFTER they are changed and do not change existing tasks
retroactively. Double click the ID number of the task(s) in question, go
the the Advanced tab of their Task Information dialog and verify that the
task type really and truly is fixed work. I know, I know ... but I've never
seen the behavior you describe in over 10 years using Project so to track
down the cause we need to check off every possibility, even those things we
think it just couldn't possibly be <grin>.


--
Steve House [MVP]
MS Project Trainer & Consultant
Visit http://www.mvps.org/project/faqs.htm for the FAQs

 

[JodyJ]

I did check that the task is set to 'fixed work'. The strange thing is that
everything behaves as expected up to a certain point. If you read my
original post, the duration was 3.09 days, units = 81%, 20 hrs of work. If I
decrease my duration to 2 days, work doesn't change. The only unexpected
behavior is the "uneven" change in units (i.e. one resource increases units
but the other doesn't). If I continue to decrease duration to 1 day, this is
when the "work" changes. Very odd. If anyone has seen this behavior, let me
know. It almost seems like it's tied to some other "work / day" limit.

 

[Steve House [Project MVP]]

You do have some interesting numbers all right. 3.09 days is 3 days and 43
minutes if your resources work an 8 hour workday and that in itself, along
with an 81% units assignment (representing thatan individualis working on
this task 6 hours and 28 minutes each workday), gives me pause to wonder
where you got such odd numbers in the first place. Why 81% and not 80% or
75% or the preferred 100%?

It just occurred to me, I wonder if your resources have different work
calendars so they aren't working concurrently. That can produce some
strange things with the work/duration relationship. For example, if
resource 1 works 1 hour on Monday and resource 2 works 1 hour on Friday, the
total work is 2 hours and the duration is 5 days. Duration is from the
point when the earliest starting resource begins until the time the latest
finishing resource finishes whether or not they are working together or are
working continuously. Could it be that they are not working together or
work different hours and that makes the durations do odd things?
--
Steve House [MVP]
MS Project Trainer & Consultant
Visit http://www.mvps.org/project/faqs.htm for the FAQs