Slack Variation

[Arthur A]

I have a series of tasks that are set with a FS relationship. There are no
lags. The early and late dates are consistant, but the total slack changes.
For example on one task the ES date is 4/7/10, the EF is 4/8/10, the LS is
2/12/10 and 2/13/10. The total slack is -61 days. OK, on a 7 day week it
doesn't equal 61 days. So that doesn't make sense to me. Next to this is
another task with an ES date of 4/4/10, an EF of 4/7/10, the LS is 2/10/10
and the LF is 2/12/10. The slack on that is -25 days. I don't understand.

Arthur A

 

[Jim Aksel]

Look for other items constraining the tasks such as deadlines or more
specifically items such as "Start No Earlier Than", "Finish No Earler Than",
etc. You can insert the constraint type and constraint date columns to see
these. You want your task type to be "As Soon As Possible"

See if that helps. Also, if your slack is negative, this is a sure sign you
have something else constraining the tasks beyond your regualr FS chain.
--
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Jim Aksel, MVP

Check out my blog for more information:
http://www.msprojectblog.com

 

[Arthur A]

I have done the check on constraints. There is one further down this path.
That is what has caused the negative slack. All the others are "As Soon As
Possible". But that doesn't explain the change in the slack value. It just
doesn't make sense to me.

Arthur A

 

[Arthur A]

I have checked for deadlines. There are none. I do have a "finish no later"
at the end of the project to provide the slack value. But the calculations
don't make any sense.

Arthur A

 

[Rod Gill]

Under Project, Project Properties, what's the finish date of the project?

What's the finish date if you select every task, press Shift+F2 and under
the advanced tab select constraint type as soon as possible?

--

Rod Gill
Microsoft MVP for Project

Author of the only book on Project VBA, see:
http://www.projectvbabook.com

I have a series of tasks that are set with a FS relationship. There are
no
lags. The early and late dates are consistant, but the total slack
changes.
For example on one task the ES date is 4/7/10, the EF is 4/8/10, the LS is
2/12/10 and 2/13/10. The total slack is -61 days. OK, on a 7 day week it
doesn't equal 61 days. So that doesn't make sense to me. Next to this is
another task with an ES date of 4/4/10, an EF of 4/7/10, the LS is
2/10/10
and the LF is 2/12/10. The slack on that is -25 days. I don't
understand.

Arthur A

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[Arthur A]

I found the issue wasn't with the constraints or deadlines. The calendar for
the task was different than the project calendar. I still don't understand
how Project calculates the slack time, but I can make the slack consistant by
ensuring the task calendar is the same as the project calendar.


Art