Problem w/ duration cal. incorrectly when applying multiple resour

[bgane]

The method I'm trying to use is to use Work & Resources to automatically
calculate Duration. As an example, I have Type set to Fixed Work. I set the
task for 15d, and then add three full-time (8hr) resources to it, one at a
time. Project correctly calculates the duration to be 5d. However, when I
set one of those resources to 50% and another to 75%, the duraction is
changed to 10d. By my calculations, it should be 6.67d (120hrs/18hrs). Am I
missing a step here?

In the same vain, I would like to add multiple resources at one time (ex: 3
75% resources at one time), but Project appears to have issues with this. I
have found a little more success adding one resource at a time.

Any help would be greatly appreciated.

 

[Steve House [Project MVP]]

When you have multiple resources on a task, the duration of the task is the
duration of the resource who is working on it the longest. In your example,
task begins at 15 days. Add three resources 1 at a time, duration shrinks
to 5 days, with each resource doing 5 man-days of work over the course of 5
days duration, all in parallel - normal effort-driven behaviour. So far, so
good. Now Resource 2 is set to 75% and Resource 3 is set to 50%. They'll
each still have to generate 5 man-days of work but at those rates it takes
Resource 2 6.67 days of duration to produce his 5 man-days of work while it
takes Resource 3 10 days to do the same. Task begins with Resources 1, 2,
and 3 working together. After 5 days have elapsed, Resource 1's portion of
the work is done and he leaves, while 2 and 3 continue without him. After
another 1.67 days have passed, Resource 2 will have completed his 5 man-days
of work and he leaves, leaving Resource 3 working alone. Finally after a
total of 10 days has passed, Resource 3 finishes his portion and the task
itself is done.

HTH

 

[bgane]

Thanks for your response. So, are you saying that the order of steps matter?
What steps should I take to consistently get the results I'm looking for?

 

[Mike Glen]

Hi bgane,

Welcome to this Microsoft Project newsgroup

You might like to have a look at my series on Microsoft Project in the
TechTrax ezine, particularly #10 Multiple Resource Assignments, at this
site: http://tinyurl.com/2xbhc or this:
http://pubs.logicalexpressions.com/Pub0009/LPMFrame.asp?CMD=ArticleSearch&AUTH=23
(Perhaps you'd care to rate the article before leaving the site,
Thanks.)

FAQs, companion products and other useful Project information can be seen at
this web address: <http://www.mvps.org/project/>

Hope this helps - please let us know how you get on

Mike Glen
MS Project MVP

 

[Steve House [Project MVP]]

This is a case where I would use the split screen to assign the resources.
Enter Task X, duration 15 days. Assign resource R1 at 100%. Total Work is
calculated at 120 man-hours. Now with the task selected split the screen.
In the bottom window you'll see R1 already assigned. With the task set to
effort driven and the task type as Fixed Units, use the pulldowns under the
existing resource to add R2, entering 75% in the units column, and R3 with
units set to 50%. Click the "OK" button. You'll see the work gets
distributed between all three resources in a 4:3:2 ratio with R1 getting
53.33 hours, R2 getting 40 hours, and R3 getting 26.67 hours while the
duration goes to 6.67 days.

Now the question remains, why don't you have R2 and R3 devote their full
attention to their work and assign them 100%? Have 'em all give it their
full efforts and just git 'er done ASAP.

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