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Summary Float

11 replies [Last post]
Thu, 2006-11-16 14:09
Dave Dodds
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Does anyone know how the float is calculated for total float in the summary bars?

Thanks
Dave
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Replies

Wed, 2007-01-03 13:30
#1
Marcio Sampaio
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Thanks a lot Vladimir,

Now it is clear to me.

Regards.

Marcio Eduardo.
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Mon, 2007-01-01 14:57
#2
Vladimir Liberzon
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Marcio,
I suggest to consider one very simple example.

Project Sample consists of 4 activities and finish milestone.
Activities 1, 2 and 4 have 10 days duration, duration of activity 3 is 1 day, activity 5 has zero duration (milestone).
Activity 2 follows activity 1, activity 4 follows activity 3. Activities 2 and 4 precede activity 5. All dependencies are Finish-to-Start.
Project resources include one unit of resource A and one unit of resource B.
Resource A is assigned to activities 1 and 3, resource B is assigned to activities 2 and 4.
Project schedule calculated by P3e using default leveling algorithm has 30 days duration – project starts with activity 1, then 2, then 4. Activity 3 is planned after activity 1 finish.
The same schedule is calculated by MS Project. These packages calculate the same resource-constrained schedules but different activity floats. Both results are wrong.
P3e shows that activity 4 has 10 days float. Can you explain this? It is interesting to understand the meaning of 10 days total float of the last activity in the schedule.
By the way the optimal schedule for this project lasts 21 day and starts with activity 3.

Try this example or any other project with limited resources. You will notice that total floats calculated in resource-constrained schedules are not feasible. Most planners do not level project resources and just do not notice serious problems with resource constrained scheduling that exist in many packages.

Happy New Year!
Vladimir
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Sat, 2006-12-30 18:15
#3
Marcio Sampaio
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Hi Vladimir,

Sorry, didnt know that. Coul u please explain me better?

Best Regards.
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Sun, 2006-12-24 14:46
#4
Vladimir Liberzon
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I hope that you know that P3e calculates wrong floats when resources are limited?
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Sat, 2006-12-23 11:03
#5
Marcio Sampaio
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-100 negative float is bigger than -1 negative float.

Regards.
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Sun, 2006-12-03 19:22
#6
Alex Wong
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Marcio

Biggest negative float is the one closer to Zero

DO you agree ??

-100 and -1 Which one is bigger??

HEHE

Alex
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Fri, 2006-12-01 19:29
#7
Marcio Sampaio
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I siad "biggest total float " ... but i was trying to say "biggest negative float"

Regards.
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Sun, 2006-11-26 20:40
#8
Alex Wong
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Dear all

A summary float under a group of activities is the "Least (minimun)" float within that group of activity

Why?? SIMPLE

because you want to know how critical is that group fo activity are when they are summarised.

Of if just one activity within that group of activity have a negative float the summary bar will also have a negative float

HTH

ALex

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Sat, 2006-11-25 17:31
#9
Marcio Sampaio
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Hi Dave;

Thanks for your explanation. Is it in the P3e manual? Could u tell me the page so i can read?

Regards.

Marcio Eduardo
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Mon, 2006-11-20 08:15
#10
Dave Dodds
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Marcio,
I found the answer in the book. The calculation is, depending on your settings (early or late), the float between the earliest early start and the latest early start for the activites under that summary level. I find it to be a confusing number for a project manager and trying to explain it didn’t help. What would be nice is if I could show the activity float without the summary.
This came about when a client p.m. asked why there was float in an area that the critical path "passed through". He ended up righting it off to another quirk of P3.
Not usefull.

Thanks,
Dave
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Sat, 2006-11-18 19:06
#11
Marcio Sampaio
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Dave;

As i know, in P3e, total float for summary bars is equal to the biggest total float in the activities that are under summary bar.

But i’m not totaly sure.

Regards.
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