Float Degregation 2

[blooda]

Hi ALL

Has anyone done any work on float degregration. i.e. the rate at which the float (Slack) of the project degrades throughout the life of the project.

Its an area I'm looking into as another way of monitoring the project Status.

Would Like to hear any Comments

RGDS

AB

 

[RDK]

Interesting concept.

I have always looked at the float as a project resource. It allows me to concentrate my efforts on those items that are on the critical path and allows me to let slide those items that are not critical. (i.e. it is the “spare” time that I have available to initiate different parts of the project in time for them to come on line before they are critical.)

As the project draws nearer to completion the number of paths available to complete becomes fewer and the amount of total slack becomes less.

If I understand your question correctly you are looking for the slack utilization rate. Is it linear? Will it follow an “S” curve like most resource utilization rates?

In order to answer this question you will have to have several completed projects with periodic updates to analyse.
Rick Kitson MBA P.Eng

Construction Project Management
From conception to completion

http://www.kitsonengineering.com

 

[blooda]

Thanks,

Yes you got it pretty much.

The critical path has no float (usually!) but the float degregation (or utilisation) I think is a good monitor for the rest of the programme.

As for the shape of the graph, someone I spoke to thought it would be the inverse of a traditional 's' curve.

But I will try a few projects as you suggest and update them regularly as if they are always on time.

RGDS

AB

 

[RDK]

You may want to look at float on not only the path with the least float but on several paths in decending order of criticality. (If that is a word?)

I'm interested in any results that you get from this work.

Rick Kitson MBA P.Eng

Construction Project Management
From conception to completion

http://www.kitsonengineering.com

 

[dhlynch]

This is a very interesting idea. I hope you keep the idea alive. I'd like to see what your results are.

 

[mainepepmp]

I agree that considering attributes of float is an interesting idea for new metrics to measure project status, but wonder if "degradation" is the best way to look at it. The word conjures up only a unidirectional image for me, I'm afraid.

Over the course of the project, the float on any path can go up or down from that originally projected when the baseline schedule was established, as a function of whether the tasks take more/less time than originally planned.

Thus, describing a situation where float increases would require use of a negative "degradation" statistic, something that feels a little counterintuitive. Two sides to every story, though--leave us not neglect to pay due homage to "negative float"!

Conventionally, positive quantities or indices > 1 are used to indicate desirable situations. (Although, depending on how much your float increased, I guess I'd have to wonder if that was actually a "good" thing, and start looking upon your duration estimation/resource planning skills with a jaundiced eye if your float kept increasing.)

That said, what about a float metric that either indexes the current float to the float in the baseline plan (<1 is bad, indicating task slippage or emergence of resource constraints), or one which measures the rate of change in the float [the change in float from time(1) to time(2), divided by the time difference between time(1) and time(2)]?

In the case of the latter situation from the paragraph immediately above, a positive rate could be taken as a &quot;good&quot; indication, as long as things didn't get TOO good, as noted previously!

Taking it way out in the ether, I guess one could also then regress these empirics across a variety of like projects that went well/according to plan, define the functional relationships in two or three dimensions, calculate their derivatives, and use them to project float performance on future projects.

I don't surf a lot of PM trade rags or professional journals, so I don't know if these ideas have yet been surfaced in refereed print before. If they strike someone's fancy as being novel, and spark an interest in publishing a paper, please leave a note on this thread for contact &quot;off-thread&quot; (so to speak) to explore mutual interest. Alternately, probably now would be a good ex-post-facto time to reconsider eng-tips' intellectual property rights provisions!

 

[BernardErtl]

Monitoring the status of non-critical tasks is essential for identifying potential problems early enough that they can be corrected.

The problem with using a straight float slippage monitoring program is twofold:[ol][li]It does not account for resource loadings. Ie. one task loaded with 10 men slipping one shift is more important than 3 tasks with 2 men (of the same craft) each slipping the same amount of time.[li]It does not account for critical resources. Some resources drive the schedule more than others. Consider the case where a turnaround is short on inspectors. Slippages in inspection tasks will be far more deleterious to the project than slippages in tasks like laborers cleaning something.[/ol]

We developed a means of measuring what we call Critical Mass - when the rate of progress for a given resource is insufficient to complete it's scheduled work within the timeframe of the Critical Path. This is similar in concept to monitoring resource loading reports to ensure the schedule's resource requirements fit within the actual workforce attendance. By monitoring this every shift, you can make adjustments as soon as potential problems are detected.


Bernard Ertl
www.interplansystems.com
- eTaskMaker Project Planning Software
- ATC Professional Turnaround Management Software

 

[simchuck]

This sounds very much like &quot;Critical Chain Project Management&quot; (CCPM). I'm not terribly well-versed in the methods, but there is a very active discussion group at CriticalChain@yahoogroups.com if you want to learn more. There are some very informed people that will most definitely give you some great ideas.