Duration between two Tasks

[Robin Roe]

Does anyone know of an easy method of calculating the duration between the
finish of one task to the start of another task? E.g. Task 1 Finishes on Mon
1-1-08 while Task 2 Starts on Mon 8-1-08. Duration = 5 days.

Thanks

 

[Mike Glen]

Hi Robin,

Welcome to this Microsoft Project newsgroup

I think you're putting the cart before the horse! You should not type in
dates. Enter the Task Name, Duration and the Precedence (logic) links.
Then let Project do what it is designed to do - create a schedule for you.
So, if Task 1 finishes on Monday, and you don't want Task2 to start for a
week, you need to create a FS link with a lag of 1 week. You can see
therefore that you have to know the duration gap to feed into Project, and
thus you don't need to calculate the gap.

FAQs, companion products and other useful Project information can be seen at
this web address: http://project.mvps.org/faqs.htm

Hope this helps - please let us know how you get on

Mike Glen
MS Project MVP
See http://tinyurl.com/2xbhc for Project Tutorials

 

[Robin Roe]

Hi Mike,

I totally agree with you and 99% of the time I would do it using the methods
you mention. I have just one or two situations where I need to work
backwards. I generally put in a dependency where tasks don't actually have a
hard dependency, but I want to keep a consistent gap between tasks if the
schedule slips. For example, resource levelled tasks. I want everything in
future to push out and keep the tasks in the same order with the same gap.
Perhaps there is a better way to achieve this?

Thanks again,

 

[Mike Glen]

Hi Robin,

Double-click on the successor task and in the Predecessors tab, add a lag to
the length of the delay you want and Project should honour that gap.

Mike Glen
Project MVP

 

[Robin Roe]

Thanks agian for the reply Mike. I realise that's what I have to do, but my
original question was to know if there was a way of working out what the lag
figure should be without manualy having to count the days.

Thanks

 

[Mike Glen]

Hi Robin,

Well, I suppose that if you actually type in a constraint date, you could
use the DateDiff function in a spare field. Insert a column. right-click to
customise and click Formula, In the dialog, search the Date functions for a
DateDiff function - use Help for the function if necessary. Maybe some vba
code would also do the job, but I'm no expert, so maybe someone else could
step in.


Mike Glen
Project MVP

 

[Steve House]

Your referral to "what the lag should be" seems the be putting the cart
before the horse. Your logic assumes you already know the finish of Task 1
and the start of Task 2 and proceeds with "Task 1 ends Tuesday at 5pm, Task
2 begins Friday at 8am, therefore the lag is 2 days." That's exactly
opposite of the way Project's scheduling engine is designed to operate. The
logic it uses assumes that the start of Task 2 is completely unknown and
proceeds "Task 1 ends on Tuesday @ 5pm, there must be at least 2 days delay
before Task 2 may start, therefore Task 2 starts Friday @ 8am." The lag is
not determined by calculating the time between two known dates. Rather, it
is the result of some condition that that says "regardless of when Task 1
ends, Task 2 should not be scheduled to occur before X time units have
passed." Perhaps it's due to a reply timne needed, perhaps it's the time
required for paint to dry or concrete to set up or a part to arrive after
it's ordered. Whatever the cause, it models a physical requirement of the
project and is not just an expression of the time between two dates on which
tasks have been arbitrarily scheduled. It can't be stressed to strongly
that Project does not simply document task dates you have already
predetermined - its job is to model the project's required physical process,
combine that with information on when assets are available, and tell you the
dates when the tasks are ABLE to take place.

HTH

 

[B Sai Prasad [PMP]]

Dear Microsoft Project User,

I understand your question as you want to calculate the number of days
between the predecessor and successor; this number would be used as lag
between the tasks.

Though, Microsoft Office Project supports custom columns with formulae
involving dates, my observation is these formalae operate on the dates of the
same task.

So, I suggest you use use Microsoft Office Excel.
1. Copy the Task Name, Start, Finish columns to the columns (A, B and C) to
Excel worksheet.
2. In the cell D2, use the formula B2-A1
3. Copy the formula to all other rows of D columns
4. Change the format of the cells to number (with 0 decimals).
Observation: Lag would be calculated in column D.

Change the "Predecessors" column to include positive or negative number;
based on whether it is a lead or lag.

Note: Microsoft Office Project does not have a field called "Lag" at task
level. So, you need to manually change the predecessors to include this
information.

Please let know if this helps.

Regards
Sai [PMP]

 

[Robin Roe]

Thank you to all who took the time to reply.
--
Robin

Dear Microsoft Project User,

I understand your question as you want to calculate the number of days
between the predecessor and successor; this number would be used as lag
between the tasks.

Though, Microsoft Office Project supports custom columns with formulae
involving dates, my observation is these formalae operate on the dates of the
same task.

So, I suggest you use use Microsoft Office Excel.
1. Copy the Task Name, Start, Finish columns to the columns (A, B and C) to
Excel worksheet.
2. In the cell D2, use the formula B2-A1
3. Copy the formula to all other rows of D columns
4. Change the format of the cells to number (with 0 decimals).
Observation: Lag would be calculated in column D.

Change the "Predecessors" column to include positive or negative number;
based on whether it is a lead or lag.

Note: Microsoft Office Project does not have a field called "Lag" at task
level. So, you need to manually change the predecessors to include this
information.

Please let know if this helps.

Regards
Sai [PMP]

Thanks agian for the reply Mike. I realise that's what I have to do, but my
original question was to know if there was a way of working out what the lag
figure should be without manualy having to count the days.

Thanks

 

[Mike Glen]

You're welcome, Robin

Mike Glen
MS Project MVP
See http://tinyurl.com/2xbhc for Project Tutorials

Thank you to all who took the time to reply.
--
Robin

Dear Microsoft Project User,

I understand your question as you want to calculate the number of days
between the predecessor and successor; this number would be used as lag
between the tasks.

Though, Microsoft Office Project supports custom columns with formulae
involving dates, my observation is these formalae operate on the dates of
the
same task.

So, I suggest you use use Microsoft Office Excel.
1. Copy the Task Name, Start, Finish columns to the columns (A, B and C)
to
Excel worksheet.
2. In the cell D2, use the formula B2-A1
3. Copy the formula to all other rows of D columns
4. Change the format of the cells to number (with 0 decimals).
Observation: Lag would be calculated in column D.

Change the "Predecessors" column to include positive or negative number;
based on whether it is a lead or lag.

Note: Microsoft Office Project does not have a field called "Lag" at task
level. So, you need to manually change the predecessors to include this
information.

Please let know if this helps.

Regards
Sai [PMP]

Thanks agian for the reply Mike. I realise that's what I have to do,
but my
original question was to know if there was a way of working out what
the lag
figure should be without manualy having to count the days.

Thanks
--
Robin


:

Hi Robin,

Double-click on the successor task and in the Predecessors tab, add a
lag to
the length of the delay you want and Project should honour that gap.

Mike Glen
Project MVP



Hi Mike,

I totally agree with you and 99% of the time I would do it using
the
methods
you mention. I have just one or two situations where I need to work
backwards. I generally put in a dependency where tasks don't
actually have
a
hard dependency, but I want to keep a consistent gap between tasks
if the
schedule slips. For example, resource levelled tasks. I want
everything in
future to push out and keep the tasks in the same order with the
same gap.
Perhaps there is a better way to achieve this?

Thanks again,
--
Robin


:

Hi Robin,

Welcome to this Microsoft Project newsgroup

I think you're putting the cart before the horse! You should not
type in
dates. Enter the Task Name, Duration and the Precedence (logic)
links.
Then let Project do what it is designed to do - create a schedule
for
you.
So, if Task 1 finishes on Monday, and you don't want Task2 to
start for a
week, you need to create a FS link with a lag of 1 week. You can
see
therefore that you have to know the duration gap to feed into
Project,
and
thus you don't need to calculate the gap.

FAQs, companion products and other useful Project information can
be seen
at
this web address: http://project.mvps.org/faqs.htm

Hope this helps - please let us know how you get on

Mike Glen
MS Project MVP
See http://tinyurl.com/2xbhc for Project Tutorials



Does anyone know of an easy method of calculating the duration
between
the
finish of one task to the start of another task? E.g. Task 1
Finishes
on
Mon
1-1-08 while Task 2 Starts on Mon 8-1-08. Duration = 5 days.

Thanks