Calculating Durations

[Glenn]

Hi all,

I am incorporating a cost estimate that I have successfully imported to
Project from Excel. I have one field named "Daily Output" and another named
"Quantity". Both are Number fields as Number1 and Number2 respectively. If
I have a Daily Output of 100 and my Quantity is 1000, then I should provide a
Duration of 10 days, if the task is not split. Can I have Project take the
values in these two fields and calculate the duration?

This post is also in the Project Developer area. Hope this is OK. Please
advise if not.

thanks,
glenn

 

[Jack Dahlgren MVP]

Double click the task and on the advanced tab that appears, set the task
type to "fixed work"
Set the work on the task to 8000 (if you are entering hours - the default) ,
create and assign a resource at a rate of 100 (or 10,000% )
The duration should show up as 10 days.

-Jack Dahlgren

 

[Glenn]

Hi Jack,

Not sure if I follow completely.

Again, I want to calculate the duration of a task that has a daily output (
Number1 as a custom field) and a quantity (Number2 as a custom field).

For example, if a resource can install 100 windows in a day (i.e. their
daily output) and they have 1,000 windows to install (i.e. their quantity),
then the duration should be 10 days.

Is there a calculation that can be done to automatically set the duration to
10 days?

 

[Jack Dahlgren MVP]

The duration can not be set using custom field formulas. But the duration
can be set using the built in work and resource units fields.
My suggestion is to use the built-in capabilities instead of using custom
field formulas and I outlined how you would do that.
It involves assigning a resource to the task, setting the amount of work and
then project will automatically calculate the duration.

-Jack Dahlgren

 

[Steve House [MVP]]

FWIW, the duration in your example is 10 days if and only if the resource is
working at it 100%. If he's working 50%, then it will take him 20 days to
do it. What you're actually calculating by dividing deliverable required by
the rate it's produced is the Work required. If 1 person can install 100
windows a day (seems like a very big number for one guy but I'll go with
your numbers), the installation of each 100 windows requires 8 man-hours of
work.

 

[Glenn]

Jack,

duration = work / assignment units

If I have 100 windows and I can install 10 windows/day with a resource at
100% assignment units then my duration=10d
where quantity = 100 windows and daily output is 10 windows/day

The problem still remains that I will need to manually enter the work in
this case 10d.

Can work be calculated automatically? The answer seems to be no. Quantity
and Daily Output should be a fundamental aspect of scheduling and if it
cannot do this, I think MSP falls short.

In each response you state that work needs to be input manually. If this is
correct, and I believe it is, then I am disappointed in MSP unless I am still
missing the big picture.

glenn

 

[Glenn]

Hi all,

I believe I have figured this out and it seems to be very simple which
usually ends up being the correct solution.

In excel, I have my estimate with Quantity and Daily Output. I create
another field in excel called work. When I import my estimate in excel to
Project, I have the excel work field be a Work field type in Project. I
assign my resources with their units and voila, I have my duration.

Feel free to comment

glenn

FWIW, the duration in your example is 10 days if and only if the resource is
working at it 100%. If he's working 50%, then it will take him 20 days to
do it. What you're actually calculating by dividing deliverable required by
the rate it's produced is the Work required. If 1 person can install 100
windows a day (seems like a very big number for one guy but I'll go with
your numbers), the installation of each 100 windows requires 8 man-hours of
work.
--
Steve House [Project MVP]
MS Project Trainer & Consultant
Visit http://project.mvps.org/faqs.htm for the FAQs

Hi Jack,

Not sure if I follow completely.

Again, I want to calculate the duration of a task that has a daily output
(
Number1 as a custom field) and a quantity (Number2 as a custom field).

For example, if a resource can install 100 windows in a day (i.e. their
daily output) and they have 1,000 windows to install (i.e. their
quantity),
then the duration should be 10 days.

Is there a calculation that can be done to automatically set the duration
to
10 days?

 

[Jack Dahlgren MVP]

You have to enter either work or quantity in any case. I don't see a
fundamental difference between the two.
I'm disappointed about many things in project and other software, but I
don't let that get in the way of getting my job done.

-Jack Dahlgren