Duration based on Quantity / Productivity Formula

J

jimec74

Hi

I'm trying to develop a schedule using the following Custom Number fields:

Quantity (Number1) units would be "cubic metres", m3, eg. of dirt
Productivity (Number2) units would be "cubic metres per hour", m3/hr,
eg. for an excavator

Whereby Duration (in hours) = Quantity / Productivity
and Quantity is a fixed figure.

I can't seem to set Duration to calculate using a formula, but have set a
2nd Duration field (Duration1) = Number1/Number2, however I got the following
result:

Quantity = 700000
Productivity = 1000
Duration1 = 1.46d clearly this is wrong, and should show something like
29.17d (= 700000 m3 / 1000 m3 per hour / 24hrs).

I have three questions here:
1) How should I be setting up a Task to get the correct Duration?
2) How do I get Duration = Duration1 (or set Duration using the formula)
3) How do I get the Durations to be reported in Hours, rather than Days?

Thanks
 
V

vanita

Hi

First I would like to give my input on the duration calculation formula. I
think you should have Duration = Qty./(Productivity * Max. no. of resources
that can be deployed at a time)

Second to change duration to hrs. do Tools > Options > Schedule > Duration
is entered in (change hrs.)

Third to get correct result for Duarion 1 column, use formula Str( [Number
1] / [Number 2]). This is as per the formula being adopted by you. You would
automatically get correct duration in hrs.

I hope it helps
Vanita
 
J

Jan De Messemaeker

Hi,

Let me try to help out on your questions.
1. All durations and work values are internally handled in minutes so your
formula yields 700 minutes which is 1.46 days of 8 hours. You have to
multiply the result by 60 to get the result in hours.
2. Since only custom fields carry formulas you cannot set Duration through a
formula. You can do it in VBA. Could you install a macro, if yes, I'l write
the code.
3. Vanita answered that one: Tools, Options, Schdedule, Duration is enetred
in...

HTH


--
Jan De Messemaeker
Microsoft Project Most Valuable Professional
+32 495 300 620
For availability check:
http://users.online.be/prom-ade/Calendar.pdf
 
D

Dave

Jan said:
Hi,

Let me try to help out on your questions.
1. All durations and work values are internally handled in minutes so your
formula yields 700 minutes which is 1.46 days of 8 hours. You have to
multiply the result by 60 to get the result in hours.
Click to expand...

And then divide by 60 twice ...
 
J

Jan De Messemaeker

Hi,

Sorry for the short reaction an hour ago, didn't have the time to
explain.When you calculate a duration from project data it comes in minutes,
when you want to show it in a text field as hours you divide by 60.
This case is the opposite.
You calculate duration from two number fieds: production divided by hourly
rate.
The user expects this to be hours and it would be if he put it in a number
or a text field.
But by putting it in a duration field he causes Project to interpret it as
minutes so if he want the duration field to show hours he has to multiply by
60.

Still in doubt? Try it
--
Jan De Messemaeker
Microsoft Project Most Valuable Professional
+32 495 300 620
For availability check:
http://users.online.be/prom-ade/Calendar.pdf
 
D

Dave

Jan said:
Hi,

Sorry for the short reaction an hour ago, didn't have the time to
explain.When you calculate a duration from project data it comes in minutes,
when you want to show it in a text field as hours you divide by 60.
This case is the opposite.
You calculate duration from two number fieds: production divided by hourly
rate.
The user expects this to be hours and it would be if he put it in a number
or a text field.
But by putting it in a duration field he causes Project to interpret it as
minutes so if he want the duration field to show hours he has to multiply by
60.

Still in doubt? Try it
Click to expand...

No problem.

I misinterpreted your reply - I understood your post as saying that to
get from 700 minutes to 1.46 8 hour days you were multiplying by 60 and
I didn't refer back to the original problem.

I should have known you wouldn't have got it wrong anyway.
 
J

jimec74

Thanks Jan

Yes, if you wouldn't mind posting a code example that'd be great. Fairly
comfortable writing VBA for Excel, but my experience with Project is
(probably obviously) fairly limited. I was hoping to get away from using
VBA, since the other users aren't that comfortable with macros.

BTW - I understood your divide by 60 note.

Thanks again,

James
 
J

jimec74

Thanks Vanita.

You're theorectically correct about incl. the no. of resources in the
equation. My "Productivity" figure accounts for this as our schedules in
mining are typically resource-driven, ie. each "Task" represents a proportion
of material allocated to a single resource. I should've realised someone
would pull me up about that!! :)

Thanks very much for your help on the formula & getting duration to show in
hours.

James


vanita said:
Hi

First I would like to give my input on the duration calculation formula. I
think you should have Duration = Qty./(Productivity * Max. no. of resources
that can be deployed at a time)

Second to change duration to hrs. do Tools > Options > Schedule > Duration
is entered in (change hrs.)

Third to get correct result for Duarion 1 column, use formula Str( [Number
1] / [Number 2]). This is as per the formula being adopted by you. You would
automatically get correct duration in hrs.

I hope it helps
Vanita

jimec74 said:
Hi

I'm trying to develop a schedule using the following Custom Number fields:

Quantity (Number1) units would be "cubic metres", m3, eg. of dirt
Productivity (Number2) units would be "cubic metres per hour", m3/hr,
eg. for an excavator

Whereby Duration (in hours) = Quantity / Productivity
and Quantity is a fixed figure.

I can't seem to set Duration to calculate using a formula, but have set a
2nd Duration field (Duration1) = Number1/Number2, however I got the following
result:

Quantity = 700000
Productivity = 1000
Duration1 = 1.46d clearly this is wrong, and should show something like
29.17d (= 700000 m3 / 1000 m3 per hour / 24hrs).

I have three questions here:
1) How should I be setting up a Task to get the correct Duration?
2) How do I get Duration = Duration1 (or set Duration using the formula)
3) How do I get the Durations to be reported in Hours, rather than Days?

Thanks
Click to expand...
Click to expand...
 

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