Rolling Up Critical and Total Slack Columns to Summary Tasks

[MT]

How does MS Project roll up total slack and critical columns of tasks to the
summary task level?

I had intuitively assumed that it was based on the final task of te summary
task, but I have a summary task with 3 sub-tasks. The first 2 are critical,
and the 3rd is not, and the summary task is showing critical.

I would like to know this, because I would like a way to report on
critical-path health at the summary task level without having to delve into
the sub-task details.

 

[John]

How does MS Project roll up total slack and critical columns of tasks to the
summary task level?

I had intuitively assumed that it was based on the final task of te summary
task, but I have a summary task with 3 sub-tasks. The first 2 are critical,
and the 3rd is not, and the summary task is showing critical.

I would like to know this, because I would like a way to report on
critical-path health at the summary task level without having to delve into
the sub-task details.

MT,
I guess my intuition is a little different than yours. Remember, a
summary line is not a task, rather it is simply a "summary" os data for
the subtasks under it. Therefore, if any one subtask of a summary is
critical, then the summary line will also show as critical. Look at it
from a parental standpoint. If one of the kids is in trouble, the parent
feels the pain.

Hope this helps.
John
Project MVP

 

[MT]

John,
Thanks for the quick turnaround.
1) The previous summary task to the one I described has 1 critical and 2
non-critical tasks and shows up as non-critical, so would you mind
re-checking the roll-up issue?

2) So can I interpret from you response that the critical path can't really
be viewed at the summary task level?

 

[John]

John,
Thanks for the quick turnaround.
1) The previous summary task to the one I described has 1 critical and 2
non-critical tasks and shows up as non-critical, so would you mind
re-checking the roll-up issue?

2) So can I interpret from you response that the critical path can't really
be viewed at the summary task level?

MT,
There are some settings that can effect how tasks are identified as
critical. For example, Tools/Options/Calculation tab. Progress can also
affect display of critical tasks as does the use of a master file with
inserted projects (one of my main test files).

Perhaps my initial response was a bit to simplistic. One thing I have
found on this newsgroup is that users often want, perhaps in response to
pressure from upper management, to use summary line data to simplify a
schedule. Unfortunately, this approach is often misleading and quite
often presents an incorrect picture. When I do critical path analysis I
always use the whole path (or paths). Even then, some interpretation is
needed to effectively understand what is going on with the schedule.
Based on this, I would recommend you NOT try to use summary level
information to view the critical path.

Hope this helps.
John
Project MVP

 

[MT]

Try again:
1) How does total slack get rolled up to the summary task level? It's not a
sum, it's not an average, it's not a max, it's not a min. My project plan
displays counterexamples for all of these algorithms.

2) If summary tasks can't be used to describe critical path, is there any
other way to report on the critical path(s) in MS Project if upper-management
doesn't want to bother with the lowest-level tasks?

 

[Jan De Messemaeker]

Hi,

I should do some tests but I've always had the idea trhjat a summary task in
this respect IS a task; it doesn't roll up but it is critical when DELAYING
ITS START WILL DELAY THE PROJECT FINISH, in other words it has total slack
0.
HTH

 

[Mike Glen]

Hi MT,

Let me have a try! First I assume you do not have any logic links attached
to summaries ( not a good idea*). Say you have a summary task which has a
mixture of critical and non-critical tasks. If the summary start is delayed
in any way, the project end date will be affected and thus it must have zero
slack. But the whole summary does not measure just the critical tasks, it
also measures the non-critical tasks. so looking at just the summaries with
critical tasks does not, as such, show the critical path. The only way to
show the full critical path is to show all tasks that have zero slack and
ignore summaries.

*See FAQ Item: 48 - Summary Task Linking. 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
Project MVP

 

[MT]

Once again, I have 2 questions and I guess I have not clarified them well.
1) WHAT IS THE ALGORITHM TO ROLL-UP TOTAL-SLACK AND CRITICAL AT THE SUMMARY
TASK LEVEL?
2) IS THERE ANY WAY TO ROLL-UP ONLY THE CRITICAL TASKS ON A PROJECT?

I have searched through the help in MS project and I cannot find information

 

[Mike Glen]

I think, MT, that you're not getting direct answers as no one knows the
precise answers Why you want that information is a mystery to me,
because, as I intimated, critical summaries are meaningless.

As for your second question, you can filter for critical tasks and select
them all and , via the Task Information dialog, Roll up Gantt bar to
summary.

Mike Glen
Project MVP

 

[John]

Once again, I have 2 questions and I guess I have not clarified them well.
1) WHAT IS THE ALGORITHM TO ROLL-UP TOTAL-SLACK AND CRITICAL AT THE SUMMARY
TASK LEVEL?
2) IS THERE ANY WAY TO ROLL-UP ONLY THE CRITICAL TASKS ON A PROJECT?

MT,
For you reference, shouting won't help. Sometimes we have to give
answers that the user doesn't like. Too bad, that's the way it is. Mike
made a excellent point about not knowing what the exact algorithm
Project uses for summary line critical path. We might be able to figure
it out but here is the more important issue. Upper management has a
nasty habit of asking for a boiled down summary of something. For some
reason you have interpreted that as wanting a boiled down value of the
critical path at summary line level. Well, I'll tell you (as three of us
already have in our previous answers), It does NOT exist.

If you calm down and remain civil, we still may be able to help you.
What is the end goal here? In other words, what is it upper management
wants to see in terms of summarizing a project? You have focused on
critical path which is one approach (invalid as we stated), but that
isn't the only way to summarize a project's health. For example, one of
the classical methods is to use earned value. It has many summary
metrics (e.g. CPI, SPI, etc.). There are also several built-in reports,
(there are 5 under View/Reports/Overview), that are basically for
management. You might want to take a look at those options before you
fly off the handle at us again.

John
Project MVP