Another Question on Task Type

[Don]

Are there any circumstances under which all of the task type settings behave
the same way, yielding the exact same set of messages? I am trying to
understand how different task type settings affect the three variables--
Units, Work, and Duration. Here is what I did:
Using the Tools, Options, Schedule Tab I changed the default Task Type and
saved my work. On a set of specific tasks, I tested all five task type
settings-- Fixed Duration/Effort-Driven, Fixed Duration/Non-Effort Driven,
Fixed Units/Effort Driven, Fixed Units, Non Effort-Driven, and Fixed Work.
With each setting, I increased and decreased the three variables on the
task-- Units, Work, and Duration. In every case, MS Project appears to have
behaved the same way because it gave me the same set of messages every time.
What could account for this? Must be some bone-headed mistake I made...

 

[Jim Aksel]

Most of the combinations result in changes to duration.
You need to look carefully at the variables and keep this in mind:

Work=Units% x Duration

What Project does is fix one (the one you select as the task type). From
there, it is an equation, you pick two, Project recalcs the third one based
on the task setting.

Fixed Units:
I change Work, duration changes
I change Duration, work changes
I change Units% and the duration *may* change depending on the amount of the
change and its direction.

What I did was play with all the possibilities and write down the results.
I documented it on a PPT slide and hung it on my wall.

I thought I put it on my blog but I guess that's on my to do list. Check
back in a day or so.... you never know when I get around to making updates.

--
If this post was helpful, please consider rating it.

Jim Aksel, MVP

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

 

[Steve House]

First of all, effort driven and non-effort driven are not task types per se.
They describe what happens when you add or remove resource names from the
list assigned to a particular task. Let's say we have a task lasting 5 days
with one guy on it, 8 hours per day. Duration is 40 hours, work is 40
man-hours. If I add another guy and the task is effort-driven, each of them
shoulders 20 man-hours of the total 40 man-hours of work and the duration
drops to 2.5 days, 20 hours. Painting a room and adding a second painter
would be an example of this type of behaviour. If the task is
non-effort-driven, the added guy picks up an additional 40 man-hours to make
a total for the task of 80 man-hours, the duration remaining the same 40
hours it started with. Add an additional attendee at a meeting would be an
example of this type of task. The effort driven setting only matters when
you add or remove bodies.

Task type .... as Jim pointed out, Work = Duration * Units, a classic linear
equation (remember Y=mX+B from high school algebra?). One independent
variable, X, you can change at will, one constant m that's fixed in value,
and one dependent variable, Y, that's recalculated whenever you change X.
In W=D*U you get to pick the constant and the independent variable. If you
pick Fixed Work and change Units, Duration changes while if you change
Duration, Units change. Make it Fixed Units and changing Work changes
Duration and vice versa. Same for Fixed Duration. If you make the task
Fixed Units and try to change Units, it will happily let you, it behaves as
if it was Fixed Work and Duration changes. Likewise changing Work on a
Fixed Work task it behaves as Fixed Units and Duration changes. Likewise
changing Duration on a Fixed Duration task will make it behave as Fixed
Units and Work changes. All of these setting are in control when you EDIT
existing resource assignments WITHOUT adding or removing entries from the
list of names assigned.

I don't view these setting as engraved in granite but rather as switches you
the scheduler uses to make sure Project makes the right calculation. The
right setting depends on the reason you're making the edit and only you know
what should happen.

HTH

 

[Jim Aksel]

I like what Steve said:

"I don't view these settings as engraved in granite but rather as switches
you
the scheduler uses to make sure Project makes the right calculation. The
right setting depends on the reason you're making the edit and only you know
what should happen."

We routinely change task types all the time when making changes on weekly
updates. For us, we default to Fixed Duration. If someone wants to change
the duration we ask if they need more work or if the assigned resource is
just working other things as well so they are not at 100% (that is the usual
answer). So, I change the task to fixed work, increase the duration (which
lowers the units% while holding the *remaining work* constant). When I am
done, I change the task type back to Fixed Duration to be compliant with the
guidance given from the program office.

Thanks for the additional input Steve
--
If this post was helpful, please consider rating it.

Jim Aksel, MVP

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