Task duration longer than sum of sub-tasks

[seven_percent]

I have a task, let's call it Development, which has three subtasks,
we'll call those Requirements, Coding, Debugging. The three subtasks
start on the same day, with no predecessors, and last the same amount
of time: 160 hours each. I would expect to see the total for
Development, then, as 160 hours. Instead, it is 168 hours. If I
change the duration of the three subtasks to 154, the duration for
Development becomes 162. Thus, the value for the parent task
Development is always 8 hours more than the subtasks. Anyone know what
causes this and how to fix it? I have similar scenarios in my project
but this is the only case where this is happening.

 

[John]

I have a task, let's call it Development, which has three subtasks,
we'll call those Requirements, Coding, Debugging. The three subtasks
start on the same day, with no predecessors, and last the same amount
of time: 160 hours each. I would expect to see the total for
Development, then, as 160 hours. Instead, it is 168 hours. If I
change the duration of the three subtasks to 154, the duration for
Development becomes 162. Thus, the value for the parent task
Development is always 8 hours more than the subtasks. Anyone know what
causes this and how to fix it? I have similar scenarios in my project
but this is the only case where this is happening.

seven_percent,
Actually your "Development" is not a task, rather it is a summary line.
As such the Duration of a summary line will be the amount of working
time between the start of the earliest subtask and the finish of the
last subtask. The fact that the summary duration is consistently 8 hours
longer than any subtask tells me that the start and/or finish dates
(including time) is not equal among the three subtasks.

John
Project MVP

 

[Catfish Hunter]

There are several possibilities.
One is the calendars may not be the same on the summary as yuor task. I
normally don't assign a calendar to a summary because I may have task with
multiple calendars.
You may want to go to Tools>Options>Schedule and make Hours your default.
Second possibility is all task are not tied FS-0. In your case this is not
what happened.
Hope this helps.

 

[seven_percent]

I checked that. They were all precisely the same.

No matter. I didn't have any more time to waste on figuring out this
fluke. Since there were only 4 items, I deleted them and recreated.
Everything is fine now. Thanks anyway.

 

[John]

I checked that. They were all precisely the same.

No matter. I didn't have any more time to waste on figuring out this
fluke. Since there were only 4 items, I deleted them and recreated.
Everything is fine now. Thanks anyway.

seven_percent.
Sorry we couldn't be of more help but sometimes the effort to figure out
why something happened takes longer than a brute force fix, like the one
you used. At least I'm glad you resolved your problem.

John