Duration Calculation

[CDAK95]

Within my project, I have several resource groups that have different
schedules (i.e. one group work 6.5 hours per day x 5 days, the second group
works 8.5 hours per day x 7 days, and the third group works 10 hours per day
x 7 days). I have set up seperate calendars for each group. However, it
appears the duration is calculated based upon a common calendar. How can I
change this function so it calculates duration based upon the work calendar
specific to each working group?

 

[Dale Howard [MVP]]

CDAK95 --

Microsoft Project calculates the Duration of every task in a project using
the following formula:

Duration = Work/(Units x Hours Per Day)

The software uses the Hours Per Day value that you set for each project by
clicking Tools - Options - Calendar. There is only one Hours Per Day
setting for each project, which the software uses to calculate the Duration
of every task in the project. Therefore, you simply cannot do what you wish
in this case. Sorry. Hope this helps.

 

[Steve House [Project MVP]]

Duration is always measured in hours (actually 10ths of minutes if you want
to get technical). Durations expressed as days, weeks, months, etc are
strictly conversions for convenience. The number of hours that is
considered "1 day" is a global setting controlled by the Hours per Day field
on the Tools, Options, Calendar page. The actual elapsed timed that
transpires from when the task begins until it ends is calculated using the
calendar that controls that task - the Project Calendar that for tasks that
do not have resources assigned and the Resource task for the assigned
resource for tasks that do.

Example:

In a project starting Monday at 8am with all the default settings I enter a
task as having "1 day" duration. 1 day = 8 hours so the "real" duration of
the task is 8 hours. The standard project calendar has an 8 hour work day.
The task begins at 8am and ends 8 working hours later, at 5pm. I assign
that task to a (very) part-time resource who works only 1 hour per day over
the lunch hour, Mon thru Fri. His work calendar shows hours of work as
12noon to 1pm, M-F. When I assign that task to him, it moves to start when
he comes in to work, 12noon on Monday. It ends when 8 of HIS working hours
have elapsed, at 1pm on Wednesday a week and a half later. That is still a
"1 day" task because the phrase "1 day duration" really means "how ever long
it takes to have been on the job for 8 working hours" (okay, 4800
deciminutes if you want to be picky <grin>) and that's what the duration in
the Gantt chart will show.

 

[CDAK95]

I am working my way around this by establishing my project calendar day as 10
hours. For the individuals who work a 6.5 hour day, I set their availability
as 65% in the resource sheet. Similarly, I set my resources on the 8.5 hour
schedule with 85% availability. Will this cause me grief in the Gantt chart?

 

[Steve House [Project MVP]]

That's not really an accurate way of doing it. What the % represents is the
portion of the resource's work time that gets converted into useful work.
If the workday is set to 10 hours and you assign the resource to a 1 day
task at 65%, it does NOT mean they're present for 6.5 hours. It means
they're physically present and working on the task for the full 10 hours but
for some reason - perhaps they're distracted talking about the Superbowl
with their buddies on the job - they're only getting 6.5 hours worth of
full-time equivalent work output accomplished. IMHO the best way do it is
to set the Project calendar and option settings to that of the most generic
schedule, or perhaps the official schedule of the managment office. Workers
who deviate from that schedule have their own modified calendars - resource
calendars - that reflect their actual hours of work. "Day's" does not
equate to "come-to-works." A part-timer who works 4 hours per day has to
come to work TWICE to get one day's work accomplished while someone who is
scheduled 12 hours on and 12 hours off does one and a half day's work each
time he comes to the property. The word "day" should be interpretted as
"one standard shift" and not "one sunrise." By that logic, a plant that
works 24/7 works 3 days duration for every 24 hour normal sunrise-to-sunrise
civil calendar day.
--
Steve House [MVP]
MS Project Trainer & Consultant
Visit http://www.mvps.org/project/faqs.htm for the FAQs

 

[CDAK95]

Thanks, Steve. I think what I would prefer to see is Elapsed Calendar days,
as opposed to Duration. Is there a field that provides this information?

 

[JulieS]

Hi CDAK95,

You can use a custom duration field to calculate how many calendar days
there are between the start of a task and the finish.

Create a new calendar (Tools>Change Working Time). Copy the Standard
calendar, name it (I used 7Day) and make Saturdays & Sundays working days.
Then insert a custom duration field ([Duration1] for example) in the task
table. Choose Tools>Customize Fields and select the [Duration1] field.
Click the Formula... button and use the following formula:

ProjDateDiff([Start],[Finish],"7Day")

In the Customize fields dialog box, click the Use Formula option for the
task and group summary rows.

This will calculate the number of calendar days between the start of the
task and the finish of the task using the 7Day calendar. .

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

Julie