Weird behavior in scheduling

[seth]

In Project 2007, I have a task with work value of 24 hours. I assign Res1 and
Res2 (100% each). Now the duration is 12 hours. So far, so good. Now, I add
one more resource Res3 (100%). Now, the behavior seems to be inconsistent.
Sometimes, the duration changes to 8 hrs. Sometimes, it changes to 16 hrs
(which is wrong). Also, when it changes to 8 hours duration (the right one),
when I reduce the resource allocation for Res3 to 50%, the duration changes
to 16 hours instead of 9.6 hours duration.
If I delete the Res3 and then add it again but this time when I add it I put
only 50%. Now it shows 9.6 hrs duration (right one). So, I think if I update
a resource allocation after it is added, it is not behaving correctly. If I
add it with the right allocation in the beginning, it behaves correctly. I am
confused.
The task type is default (fixed units with effort driven checked).
I am not sure what is going on? User error , bug in the tool???

Any help is appreciated.

Thanks,
seth

 

[JulieS]

Hi Seth,

My comments are inline.

In Project 2007, I have a task with work value of 24 hours. I assign
Res1 and
Res2 (100% each). Now the duration is 12 hours.

[Julie] Only if you assign Res1 and let Project calculate 24 hours of
work. Then assign Res2 to an effort-driven fixed unit (or fixed work
task).

So far, so good.

[Julie] So we have a task with 2 resources (Res1 and Res2) each
assigned at 100% with 12 hours of work each on a task duration of 12
hours. Total work on the task is 24 hours.

Now, I add
one more resource Res3 (100%). Now, the behavior seems to be
inconsistent.
Sometimes, the duration changes to 8 hrs.

[Julie] Assuming Res3 has the same calendar working time as Res1 and
Res2 -- each having working time of 8 hours per day, no non-working
time. Then yes, the duration of the task is now 8 hours -- each
resource is assigned at 100% and is scheduled for 8 hours of work.

Sometimes, it changes to 16 hrs

(which is wrong).

[Julie] Changes what to 16 hours -- duration? Have you changed Res3's
calendar to have a nonworking day?

Also, when it changes to 8 hours duration (the right one),
when I reduce the resource allocation for Res3 to 50%, the duration
changes
to 16 hours instead of 9.6 hours duration.

[Julie] Again, it all depends. If Res3 has 8 hours of work to
accomplish and you drop the assignment units to 50%, Res3 now needs 16
hours of duration to get 8 hours of work accomplished. A 50%
assignment unit means that Res3 only produces .50 hour of work for
every one hour that passes in the task duration. Assigning a resource
at 50% does not assign them "half time."

If I delete the Res3 and then add it again but this time when I add
it I put
only 50%. Now it shows 9.6 hrs duration (right one).

[Julie] If you remove Res3 the total amount of work on the task stays
at 24 hours and the duration increases to 12 hours. If you assign
Res3 at 50% the 12 hours is split as follows:
Res1 - 9.6 hours
Res2 - 9.6 hours
Res3 - 4.8 hours

All three resources start and end their work at the same time,
duration is now 9.6 hours.

So, I think if I update
a resource allocation after it is added, it is not behaving
correctly.

[Julie] No, it is behaving correctly -- what you are missing is the
connection between Duration assignment units and work. I suggest
splitting your screen (Window > Split) to show the task form in the
bottom pane. You should now be able to see all three pieces. See the
online help topic "The duration or work value changes unexpectedly
when I assign a resource."

If I
add it with the right allocation in the beginning, it behaves
correctly. I am
confused.
The task type is default (fixed units with effort driven checked).
I am not sure what is going on? User error , bug in the tool???

[Julie] Actually it is neither a user error or bug Just some
fairly natural confusion. I suggest taking a look at the help topic I
suggested. Also, fellow MVP Mike Glen has an excellent series of
online tutorials about MS Project. You may view them at:

http://project.mvps.org/mike's_tutorials.htm

Any help is appreciated.

Thanks,
seth

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

Julie
Project MVP

Visit http://project.mvps.org/ for the FAQs and additional information
about Microsoft Project

 

[seth]

Hi Julie,

Thanks for your detailed response. A few additional inputs.

All resources share the same calendar and they all have same working times.

This is what I expected Project to calculate.

Res1 - 9.6 hours
Res2 - 9.6 hours
Res3 - 4.8 hours

Basically, as you put (or remove) more resources, the work remains the same
but the duration gets changed. My confusion came when I reduced the resource
3 to 50% but the duration got changed to 16 hours instead of 9.6 hours.

Also, your comment "Assigning a resource at 50% does not assign them "half
time."'. If this is not the case, then how do I assign a resource 'half time'?

The split window really helps to look at the data in detail but the other
articles does not address this very clearly.

Thanks,
seth

Hi Seth,

My comments are inline.

In Project 2007, I have a task with work value of 24 hours. I assign
Res1 and
Res2 (100% each). Now the duration is 12 hours.

[Julie] Only if you assign Res1 and let Project calculate 24 hours of
work. Then assign Res2 to an effort-driven fixed unit (or fixed work
task).

So far, so good.

[Julie] So we have a task with 2 resources (Res1 and Res2) each
assigned at 100% with 12 hours of work each on a task duration of 12
hours. Total work on the task is 24 hours.

Now, I add
one more resource Res3 (100%). Now, the behavior seems to be
inconsistent.
Sometimes, the duration changes to 8 hrs.

[Julie] Assuming Res3 has the same calendar working time as Res1 and
Res2 -- each having working time of 8 hours per day, no non-working
time. Then yes, the duration of the task is now 8 hours -- each
resource is assigned at 100% and is scheduled for 8 hours of work.

Sometimes, it changes to 16 hrs

(which is wrong).

[Julie] Changes what to 16 hours -- duration? Have you changed Res3's
calendar to have a nonworking day?

Also, when it changes to 8 hours duration (the right one),
when I reduce the resource allocation for Res3 to 50%, the duration
changes
to 16 hours instead of 9.6 hours duration.

[Julie] Again, it all depends. If Res3 has 8 hours of work to
accomplish and you drop the assignment units to 50%, Res3 now needs 16
hours of duration to get 8 hours of work accomplished. A 50%
assignment unit means that Res3 only produces .50 hour of work for
every one hour that passes in the task duration. Assigning a resource
at 50% does not assign them "half time."

If I delete the Res3 and then add it again but this time when I add
it I put
only 50%. Now it shows 9.6 hrs duration (right one).

[Julie] If you remove Res3 the total amount of work on the task stays
at 24 hours and the duration increases to 12 hours. If you assign
Res3 at 50% the 12 hours is split as follows:
Res1 - 9.6 hours
Res2 - 9.6 hours
Res3 - 4.8 hours

All three resources start and end their work at the same time,
duration is now 9.6 hours.

So, I think if I update
a resource allocation after it is added, it is not behaving
correctly.

[Julie] No, it is behaving correctly -- what you are missing is the
connection between Duration assignment units and work. I suggest
splitting your screen (Window > Split) to show the task form in the
bottom pane. You should now be able to see all three pieces. See the
online help topic "The duration or work value changes unexpectedly
when I assign a resource."

If I
add it with the right allocation in the beginning, it behaves
correctly. I am
confused.
The task type is default (fixed units with effort driven checked).
I am not sure what is going on? User error , bug in the tool???

[Julie] Actually it is neither a user error or bug Just some
fairly natural confusion. I suggest taking a look at the help topic I
suggested. Also, fellow MVP Mike Glen has an excellent series of
online tutorials about MS Project. You may view them at:

http://project.mvps.org/mike's_tutorials.htm

Any help is appreciated.

Thanks,
seth

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

Julie
Project MVP

Visit http://project.mvps.org/ for the FAQs and additional information
about Microsoft Project

 

[JulieS]

Hi Seth,
In line.

Hi Julie,

Thanks for your detailed response.

[Julie] You're welcome.

A few additional inputs.

All resources share the same calendar and they all have same working
times.

This is what I expected Project to calculate.

Res1 - 9.6 hours
Res2 - 9.6 hours
Res3 - 4.8 hours

[Julie] Then you need to assign R1. Then R2. Then R3 at 50%. You
cannot assign R3 and then drop the assignment units. Dropping the
units for a resource will make Project leave the work stable and
recalculate the duration required to get the same amount of work done
in a longer period of time.

Basically, as you put (or remove) more resources, the work remains
the same
but the duration gets changed.

[Julie] Yes, if the task is effort driven and you add or subtract
resources.

My confusion came when I reduced the resource
3 to 50% but the duration got changed to 16 hours instead of 9.6
hours.

[Julie] That was because the resource wasn't initially scheduled for
4.8 hours, h/she was scheduled for 8 hours.

Also, your comment "Assigning a resource at 50% does not assign them
"half
time."'. If this is not the case, then how do I assign a resource
'half time'?

[Julie] It depends upon what you mean by half-time. If you want to
have the resource only work four hours per day, you can change his/her
calendar to only allow 4 hours per day. A 50% assignment unit means
the resource can only produce 1/2 hour of effort in 1 hour of
duration. (Literally 30 seconds for every minute). The resource is
still "engaged" for the entire hour and would have 50% availability
for other tasks.

The split window really helps to look at the data in detail but the
other
articles does not address this very clearly.

Thanks,
seth

[Julie] You're welcome. I hope this helps.

Hi Seth,

My comments are inline.

In Project 2007, I have a task with work value of 24 hours. I
assign
Res1 and
Res2 (100% each). Now the duration is 12 hours.

[Julie] Only if you assign Res1 and let Project calculate 24 hours
of
work. Then assign Res2 to an effort-driven fixed unit (or fixed
work
task).

So far, so good.

[Julie] So we have a task with 2 resources (Res1 and Res2) each
assigned at 100% with 12 hours of work each on a task duration of
12
hours. Total work on the task is 24 hours.

Now, I add
one more resource Res3 (100%). Now, the behavior seems to be
inconsistent.
Sometimes, the duration changes to 8 hrs.

[Julie] Assuming Res3 has the same calendar working time as Res1
and
Res2 -- each having working time of 8 hours per day, no non-working
time. Then yes, the duration of the task is now 8 hours -- each
resource is assigned at 100% and is scheduled for 8 hours of work.

Sometimes, it changes to 16 hrs

(which is wrong).

[Julie] Changes what to 16 hours -- duration? Have you changed
Res3's
calendar to have a nonworking day?

Also, when it changes to 8 hours duration (the right one),
when I reduce the resource allocation for Res3 to 50%, the
duration
changes
to 16 hours instead of 9.6 hours duration.

[Julie] Again, it all depends. If Res3 has 8 hours of work to
accomplish and you drop the assignment units to 50%, Res3 now needs
16
hours of duration to get 8 hours of work accomplished. A 50%
assignment unit means that Res3 only produces .50 hour of work for
every one hour that passes in the task duration. Assigning a
resource
at 50% does not assign them "half time."

If I delete the Res3 and then add it again but this time when I
add
it I put
only 50%. Now it shows 9.6 hrs duration (right one).

[Julie] If you remove Res3 the total amount of work on the task
stays
at 24 hours and the duration increases to 12 hours. If you assign
Res3 at 50% the 12 hours is split as follows:
Res1 - 9.6 hours
Res2 - 9.6 hours
Res3 - 4.8 hours

All three resources start and end their work at the same time,
duration is now 9.6 hours.

So, I think if I update
a resource allocation after it is added, it is not behaving
correctly.

[Julie] No, it is behaving correctly -- what you are missing is
the
connection between Duration assignment units and work. I suggest
splitting your screen (Window > Split) to show the task form in the
bottom pane. You should now be able to see all three pieces. See
the
online help topic "The duration or work value changes unexpectedly
when I assign a resource."

If I
add it with the right allocation in the beginning, it behaves
correctly. I am
confused.
The task type is default (fixed units with effort driven
checked).
I am not sure what is going on? User error , bug in the tool???

[Julie] Actually it is neither a user error or bug Just some
fairly natural confusion. I suggest taking a look at the help
topic I
suggested. Also, fellow MVP Mike Glen has an excellent series of
online tutorials about MS Project. You may view them at:

http://project.mvps.org/mike's_tutorials.htm

Any help is appreciated.

Thanks,
seth

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

Julie
Project MVP

Visit http://project.mvps.org/ for the FAQs and additional
information
about Microsoft Project