PERT on 'Work' - not 'Duration'

[Johannes Nyholm Jørgensen]

MS Project 2000 (which I have) and Project 2003 has only PERT on 'Durations'.
I need to do PERT Analysis on 'Work'; Duration should be auto-updated using
the 'Work' (and 'Work' should be a result of a Optimistic, Expected, and
Pessimistic' work estimation).

NOTE: PERT on duration does NOT work!
See below: 'Uple', 'gøj' and 'UPPEGØJ' is sub-tasks of 'palle'.
But 'palle' Duration = UPPEGØJ Duration!!;
'palle' Duration should be = 3,17+4,83+21,67!
-----------
Task name ; Duration; Optimistic ; Expected ; Pessimistic
palle 21,67 days? 10 days 20 days 30 days
uple 3,17 days? 2 days 3 days 4 days
gøj 4,83 days? 4 days 5 days 5 days
UPPEGØJ 21,67 days? 10 days 20 days 30 days
GUGI 8,17 days? 7 days 8 days 9 days
NØBSESØF 7,17 days? 6 days 7 days 8 days
Ippernib 8,17 days? 7 days 8 days 9 days
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[JulieS]

Hi Johannes,

A couple of questions/comments:

In your example below, if the subtasks uple, gøj, and UPPEGØJ are not
linked, the duration of palle is correct. The duration of a summary task is
not the sum of the durations of the subtasks. A summary task's duration is
the amount of working time from the start of the earliest subtask to the
finish of the latest subtask. If all 3 subtasks start on the same day, then
the finish of the latest (UPPEGØJ) is what is driving the duration of the
summary task.

You can use four custom Number fields to calculate a PERT-type value for
work. Set the optimistic work, expected work, and pessimistic work values
in the first 3 Number fields and then use the fourth Number field to perform
the calculation. You could then copy and paste the weighted work values to
the Work field.

However, those weighed work values have *no* impact on duration until you
assign resources. The relationship between Work and Duration is:
Duration * Units = Work.

Until you assign resources to the tasks, there is no mathematical
calculation occurring.

I hope this helps. Let us know how you get along.

Julie

"Johannes Nyholm Jørgensen" <Johannes Nyholm
Jø[email protected]> wrote in message
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[Johannes Nyholm Jørgensen]

Hi JulieS,

Thanks for the good answer. It solved it! I have done as you suggested;
creating 4 custom fields etc.
I really do not understand why Microsoft has not put in support for 'PERT on
Work', like they have 'PERT for Duration'.

Johannes

 

[JulieS]

Hi Johannes,

You are welcome for the answer and glad to know it helped solve your
dilemma. As far as the why question -- sorry, I gave up long ago trying to
fathom the reasoning why for all software -- including Project ;-).

Thanks for the feedback.
Julie

"Johannes Nyholm Jørgensen"