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MSP -v- P3 -v- Powerproject

106 replies [Last post]
Thu, 2003-12-04 22:17
#91
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[Inappropriate message deleted by moderator. Please be cordial to members and guests.]
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Thu, 2003-12-04 12:27
#92
Darrell ODea
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P3 "Rules"

Dats wat I tink.
D
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Thu, 2003-12-04 10:46
#93
Bernard Ertl
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Daya, where have I posted anything specific to Power Project that could support your musings?

Bernard Ertl
InterPlan Systems Inc. - Project Management Software, Project Planning Software
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Thu, 2003-12-04 06:11
#94
Daya Sugunasingha
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IMHO I agree with every word of David Bordoli’s post and subsequent reply.
Those of you who may have used Microplanner in years gone by would agree that it did used activity on the node networks.
I also wonder if Bernard Ertl thinks that Power Project and Power Point are the same product?
Daya
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Wed, 2003-12-03 04:39
#95
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Hi PPers,

Following some lively interest in the ’Powerproject’ subject we have now created a new Forum Category especially for you Powerproject Guru’s.

We hope that this will be of interest to you?

Regards.
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Tue, 2003-11-18 05:44
#96
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OOPS yes I meant Powerproject in my last (and first) post
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Tue, 2003-11-18 05:42
#97
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The formula I referred to earlier is in fact the heuristic algorithm (possibly Polynomial.)

The point I was making about this was that MSP certainly didn’t use it in earlier versions (upto MSP 2000) and was trying to ascertain whether P3 and Powerpoint do, as for time constrained projects it is a vital tool to use so the optimised solution is known.

My personal opinion is that presentation of detailed barchart is the worst format to ’pass downwards’ but this is obviously dependant on activity numbers - I am of the old school that believes in Multi-level plans each targetted at various levels of the organisation.
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Fri, 2003-11-14 09:59
#98
Bernard Ertl
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... you should be more considerate of your language ...

Yes, I concede, I did not phrase that well. Please accept my sincere apology. I am sorry.

On first reading I do not quite understand what you mean by FF relationships require calculating early starts ‘backwards’. I thought early starts (or earliest times) were calculated on the forward pass and late starts (or latest times) on the backward pass.

Yes, but PDM systems are calculating the early starts "backwards" for FF & SF relationships on the forward pass.

The FF relationship in most PDM implementations determines the early start for a task. This can only be accomplished by using a backwards calculation from the related task as the anchor. Thus, the early start calculations have two (or more) possible basis points if FF relationships are used within the logic network. See Joe Mansours post in the Contiguous or Interruptable thread for more background on the pitfalls involved in this.

I believe that it is possible to construct a network schedule without concurrent SS & FF relationships that represent the same structure. That is why I believe that the characterization of a "fundamental flaw" is unfair (regardless of what software the original comment was targeting).

I think we will have to agree to disagree on this.

Agreed.

Bernard Ertl
InterPlan Systems Inc. - Project Management Software, Project Planning Software
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Fri, 2003-11-14 07:25
#99
David Bordoli
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Hi Forum Guest

Thanks for your comments… I was beginning to think this was an insignificant battle of semantics between Bernard and I!

You are absolutely correct about buy-in. In the UK Construction Industry at least bar charts are the norm for communicating plans upwards and downwards. I suppose it depends on the target of your audience but few in my industry would understand an A-o-L or A-o-N diagram.

I am not absolutely sure about your second point (it’s Powerproject by the way!) but I’ll do my best to get an answer for you.

Regards

David
dbordoli@burofour.co.uk

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Fri, 2003-11-14 07:16
#100
David Bordoli
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Bernard…

Whilst I have more important things to do than respond I do not wish to give the impression of tacit acceptance of what you say.

I think if you wish to sling around such comments as “But I guess it depends on whether you are painting pictures or performing critical path analysis...” you should be more considerate of your language – maybe you meant, “… it depends whether one is painting pictures … “. I think you will agree that there is a world of difference in the direction of these two statements.

On first reading I do not quite understand what you mean by FF relationships require calculating early starts ‘backwards’. I thought early starts (or earliest times) were calculated on the forward pass and late starts (or latest times) on the backward pass.

In the extract from Bramble and Callahan that you cite I see no discussion on the integrity of early start/early finish. They appear to be considering the values of start float, activity float, and finish float which are an important factor in their discussion of Construction Delay Claims.

Having said that the comment that I originally reported was “MSP 2003 they have the fantastic fundamental flaw of only allowing one link between two tasks. ie you cannot have a SS and FF between the same tasks”. As you can see this is related to a particular software. One, which as I understand does not subscribe to your view of classic definition of a critical path method scheduling. In that case, and in relation to the methods it employs to schedule projects, calculate critical paths etc, I am in agreement with Richard Ormerod that it is a pretty fundamental flaw.

As you know the legal profession’s view of scheduling is not the same as the pragmatic view required by practitioners. Questions of float are important but there is already a view (in the UK at least following the publication of the SCL Protocol) that practitioners will modify the way they construct networks to eliminate float to protect them during potential disputes but, as a consequence, will reduce their flexibility in carrying out the works.

We have to move on. As an analogy; Newton’s Laws of Motion took over from the Greek and other philosophers views of time and motion and even now Einstein’s Theory of Special Relativity has revisions. Classic theory is only good until a new classic theory comes along. I think it is probably time to move on from the developments of 1958/59 – techniques had to be relatively simple then, without number crunching computers the theory and practice was necessarily simple to match the resources of the time.

I think we will have to agree to disagree on this.

Regards

David
dbordoli@burofour.co.uk

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Fri, 2003-11-14 06:52
#101
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Firstly, In response to David, I have always used Activity-on-Arrow networks during my 25 or so years. Even in my current role, we went away from the corporate PDM tool to one that supports ADM purely because those who really dont give a hoot about plans but are an integral part (ie the assigned resources) thought that ADM was the simplest to understand. This is a key element in our attempts to get the all important buy-in so projects could (and indeed were) completed in acceptable timescale. The use of hammocks (sponge) is limited to management and Support activities for cost purposes only.

Secondly, To get back to the original subject: On a technical note which aggregation algorithm do MSP/P3/Powerpoint use?
I know that MSP certainly used a serial one at one point as opposed to the parallel algorithm. If a project is time-constrained, it is a must that the tool will give optimised results.


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Wed, 2003-11-12 14:08
#102
Bernard Ertl
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David,

It looks like I am the one who touched a nerve. Sorry to ruffle your feathers (so to speak).

...IMHO a ‘discussion’ requires more than one contributor or opinion...

Agreed. Im looking forward to more participation on the issues raised. The topic I linked is still fairly new.

I do take a little exception to your veiled critism and suggestion that I may be...

I made no criticisms or suggestions targeting you. My comments were directed towards the use of FF relationships (in general) which require calculating early starts "backwards" - which is contrary to the definition of the critical path method. The integrity of early start/early finish is compromised when there is more than one basis (as mentioned by Bramble and Callahan).

And who mentioned hammocking?

Sorry, I was being too loose with terminology. I meant tasks/activities that used both a SS & FF relationship between them.

If you advocate the use of SS dependencies then you must also have FF dependencies (or at least a FS or imposed finish tying down the end). If not it is impossible to have a critical path ...

As mentioned previously, early starts for FF relationships must be calculated in a reverse direction (which is incompatible with the definition of the critical path method). In cases where a SS relationship is used, I agree that a FS relationship must be used to establish the end point relationship for the task within the logic network.

... exactly the sort of thing that virtually all project management software uses as it’s preferred method of communicating the plan ...

I am aware that PDM scheduling is popular. That does not provide a logical basis for claiming that the lack of ability to use of a SS & FF tie between two activities is a fundamental flaw. I believe I have taken a position of arguing fundamentals when I am discussing the application of scheduling relationships with regards to the critical path method.

My comments are not personal or related to any particular software. I am merely pointing out what is IMHO, an unfair characterization.

Bernard Ertl
InterPlan Systems Inc. - Project Management Software, Project Planning Software
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Wed, 2003-11-12 12:51
#103
David Bordoli
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Bernard…

Thank-you for your forthright contribution. I am relieved that your statement is IYHO and IMHO a ‘discussion’ requires more than one contributor or opinion – but hey, lets not be pedantic here. However, I do take a little exception to your veiled critism and suggestion that I may be painting pictures rather than performing critical path analysis.

Even though I started using critical path analysis in the construction industry a mere 25 years ago I have never come across anyone who used Activity-on-Line, even way back then we were using Activity-on-Node and sending the stuff away to be computer analysed.

Things, and methods have developed and improved a bit and we can’t always depend on Classical Theory – I know some people do still subscribe to the world being flat but hey ho…

And who mentioned hammocking? I seem to remember that without the use of dummy activities A-o-N depends on ‘FS dependencies’ only. I almost can’t be bothered with this ‘discussion’ it is so facile! If you advocate the use of SS dependencies then you must also have FF dependencies (or at least a FS or imposed finish tying down the end). If not it is impossible to have a critical path – when I construct a programme (schedule?) I try to ensure the project has one start date and one end date and all activities have a start dependency and a finish dependency.

IMHO, again, I tend to think that Richard Ormerod at Asta does know what he is talking about. Serious planners could do worse than read his seminal paper on simulation (Bennett J & Ormerod R N. Simulation Applied to Construction Projects. Construction Management & Economics, vol 2. E & F N Spon, 1984). In there you might just glimpse the first demonstration of ‘linked bar charts’ and their use in critical path analysis – exactly the sort of thing that virtually all project management software uses as it’s preferred method of communicating the plan.

Whilst knowing nothing about ’eTaskMaker™ project planning software’ I am beginning to wonder if I touched a raw nerve?

Regards

David
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Wed, 2003-11-12 11:53
#104
Bernard Ertl
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[quote]Even in MSP 2003 they have the fantastic fundamental flaw of only allowing one link between two tasks. ie you cannot have a SS and FF between the same tasks - so once one has started there are no restraints![/quote]

It can be argued that allowing FF restraints as mentioned above is not compatible with the critical path method. See the What relationships are compatible with the critical path method discussion.

IMHO, claiming the lack of a hammocking (or even just the lack of FF relationships for that matter) is a fundamental flaw is quite a reach. But I guess it depends on whether you are painting pictures or performing critical path analysis...

Bernard Ertl
InterPlan Systems Inc. - Project Management Software, Project Planning Software
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