RSS Feeds :: System Dynamics Discussion Forum - Forums > Open Discussion

Board statistics

Board started:	Sat Jan 10, 2009 1:37 pm	Days since started:	605
Board version:	phpbb 3.0.6	All times are :	UTC - 5 hours
Number of posts:	869	Posts per day:	1.44
Number of topics:	178	Topics per day:	0.29
Number of users:	294	Users per day:	0.49
Our newest member :	Seyed Ali Marjaie
Most users ever online was 133 on Wed Jul 07, 2010 1:17 pm

Call for Applications on the PhD Program in: "Model Based Pu

2289 — 2010-09-04T07:11:06-04:00

I'm glad to inform you that the University of Palermo has issued a call for applications for the International PhD Program in "Model Based Public Planning, Policy Design, and Management".

8 positions (4 of which with a scholarship provided by the University of Palermo) will be available.

More info at:
(1) "http://www.ced4.it/pages/struttura/main.php?sezione=-7&__utma=20380458.447058227.1283539232.1283586418.1283592498.3&__utmz=20380458.1283586418.2.2.utmccn=%28referral%29|utmcsr=europeansystemdynamics.eu|utmcct=/|utmcmd=referral&__utmc=20380458&__utmb=20380458&PHPSESSID=15498f0e12c990ff69b7d83ea8f6ee8a"

(2) "http://portale.unipa.it/amministrazione/arearicercasviluppo/formazioneperlaricerca/home/dottorati.html"

Best regards,

Carmine Bianchi
Full...

Statistics : Posted by Carmine Bianchi • on Sat Sep 04, 2010 6:11 am • Replies 0 • Views 14

I wasn't there, but the Seoul meeting was great!

5452 — 2010-09-02T14:37:43-04:00

I cam across this in my incessant wanderings over the web: at "http://dormgrandpop.blogspot.com/2010/07/what-one-hopes-for-in-professional.html"

Congratulations to all.

"Friday, July 30, 2010

What one hopes for in professional meetings but rarely, if ever, encounters

July 30th
The occasion of my brief Korean trip was System Dynamics Society Annual meeting. The Society meetings are what one hopes conventions and association meetings will provide - high quality papers, conversations with colleagues sharing common interests, an opportunity to make new friends and a remarkable sense of community.
.........

Even if you feel you have no interest in System Dynamics modeling or have never even heard of it, you should check out the System Dynamics Society website and even consider attending an annual meeting (the next will be in July 2011 in Washington DC). The experience will rem...

Statistics : Posted by Richard Dudley • on Thu Sep 02, 2010 1:37 pm • Replies 0 • Views 30

New eBook on business applications

2016 — 2010-08-21T05:01:25-04:00

I am pleased to announce publication of a new e-book - "Strategy Dynamics Essentials". This is summarised and updated from Strategic Management Dynamics (Wiley, 2008), and follows the same chapter structure.
The book is delivered as a personalised PDF - see http://www.strategydynamics.com/essentials, where there is also a full description and outline of the book's content.
The value of system dynamics to strategy and business management is explained at http://www.strategydynamics.com/info/what-is-strategy-dynamics.aspx.
Kim Warren

Statistics : Posted by Kim Warren • on Sat Aug 21, 2010 4:01 am • Replies 0 • Views 327

Re: Sustainable Development Simulation (SDSIM)

11279 — 2010-08-10T17:32:44-04:00

well, again, aside from the difficulty of gathering a reference mode for such data, I'm not sure it is measuring anything useful. You could have a situation where someone is very interested in an issue -- be it gender equity, racial equity, environmental concerns, (or product quality, profit, on time order delivery) etc - and they may be taking many actions that reflect those concerns, yet in the system as it structured those actions may not be having any effect, or could be having an overall negative effect.

Statistics : Posted by Eric Stiens • on Wed Aug 04, 2010 12:07 pm • Replies 6 • Views 285

list of ISI Jjournals work on system dynamics articles

12314 — 2010-08-08T00:05:51-04:00

please help me to find all of journals are working on[u] system dynamics TOPIC AND THEIRE IMPACT FACTOR
THANKS ALOT

Statistics : Posted by J. Hosseini • on Sat Aug 07, 2010 11:05 pm • Replies 0 • Views 173

Re: Economics is hard...

2016 — 2010-08-02T10:42:48-04:00

It's great to see someone argue strongly for placing more value on the views of people with deep professional training in their field, than on the opinion of uninformed amateurs. We unfortunately seem to be moving to an environment in which the 'belief' of people with no knowledge of the topic is given equal if not greater weight than the skilled working out of experienced technical experts, e.g. whether we need to act on climate change seems to be increasingly a choice driven by informal referenda carried out by the media.
But a question I would ask in this case is - how much does post-graduate education in economics actually include any rigorous training in how to tackle "a topic almost pathologically riddled by dynamic considerations and feedback eﬀects" - be that system dynamics or any other suitable tool?

Statistics : Posted by Kim Warren • on Fri Jul 30, 2010 10:34 pm • Replies 1 • Views 231

Re: SD 2010 - Seoul Korea

11279 — 2010-07-29T20:58:09-04:00

Robert Eberlein wrote:Jay Write Forrester

sleep deprivation must still be in operation

Statistics : Posted by Eric Stiens • on Sat Jul 24, 2010 5:17 pm • Replies 6 • Views 309

Re: Licensing & copyright issues for models

5058 — 2010-07-29T12:05:56-04:00

Hi Ralf
The problem of openness depends on the consultant and his client and probably on his problem.
Some people feel that they will get more in return by sharing, some not.
I have worked with a consultant and if he wishes to use or modify the model for another client, he may do it, I do not mind, because I feel that I may have some small chance to get something back and no chance of losing something. He may even publish it, I do not mind. But it is a personal point of view, and I have noticed in my profession that one has generally more interest to share than protect oneself.
Regards.
JJ

Statistics : Posted by Jean-Jacques Lauble • on Thu Jul 15, 2010 3:48 pm • Replies 13 • Views 935

Opinios about topics to develop with systems dynamic

12735 — 2010-07-29T12:01:51-04:00

HI,

I wish to know information about the following topics:
Dynamic SWOT,
Dynamic Balance Scorecard,
Supply and Demand of the sustainable tourism model,
Systems Dynamic model for Risk Analyst as one key analysis for the Information security plan.
System Dynamics as the methodology to find agreements and better mental models in the analysis of environmental, communication, water, property, land and education laws of a country

My objective is to do my investigation and develop of dynamic systems in theses topics

key link: Ecuador Life at its purest, your experience of life sharing with courteous people in the diversity of nearby worlds
"http://es-la.facebook.com/pages/Ecuador-My-CountryI-was-live-have-heard-will-be-in-Ecuador/133548023343324"

Best Regards,
Francisco

Statistics : Posted by Francisco Villacís • on Thu Jul 29, 2010 11:01 am • Replies 0 • Views 168

Re: Maintaining a Model Library

2456 — 2010-07-12T09:17:07-04:00

Since posting the question I have come across Agent Ransack ("http://www.mythicsoft.com/page.aspx?type=agentransack&page=home"). I use Powersim Constructor and it is able to search through the native file format and find any text string.

Advantages: It is thorough and so far has found every occurrence of a text string I have tested. It searches through the fields in the Properites dialogue box, as well as through the model itself. So it will find text strings that are variable names as well as search the documentation and units of any variable.

Disadvantages: It does not (at least I have not found it possible) build a database, so every search is a new search. This can be time consuming depending on the folder's rank in the hierarchy.

I have now started to add a Keywords list in the Properties dialogue box and am now able to find models that I had forgotten about.

As to...

Statistics : Posted by Bill Braun • on Sat Jun 05, 2010 6:41 am • Replies 7 • Views 2240

Re: Group dynamics put into CLD

5058 — 2010-07-10T16:26:58-04:00

Hi Ralf

I am not sure of what you are trying to do.

From what I have read, you are trying to build a model that describes the inrerpersonnal relatiionshis between the people belonging to the group.
I am right?
But what kind of group is it?
What is this group working on? They must do someting in common to generate any change in their relationshisp?
Of maybe I did not understand at all your message.
Why not use the common English language to describe exactly what your model is trying to do, before drawing a CLD?
The Englisn language is based on a thousand years long languages experimentation, probably not much formalised, but still extraordinary powerful at least at describing a problem.
It cannot of course generate any simulation but at least it can alreday describe any perceived reality which is already not so bad and probably much better than any computer language (to my opinion!).
Regards.
Jean-Jacques Laublé Allocar Strasbourg France

Statistics : Posted by Jean-Jacques Lauble • on Thu Jul 01, 2010 5:17 am • Replies 2 • Views 225

Re: I am studying system dynamics with the road maps

12735 — 2010-07-06T12:25:42-04:00

Thanks Tom for your help.

The division by zero presumably arises because "desired inventory" ...It's hard to see how this could happen with the "demand price schedule" as listed in the d-memo... Yes, It was the reason for that after the model is executed, the data curves of the model are zero.

With your answers, I have understood, that I have to keep on with the road maps in order to know how improve the models and can drive the specific errors, and calibrate one model in order to get one stable result.

On the other hand, when I finished the road maps I wish to concentrate my studies in create some models, for example, Dynamic SWOT, Dynamic Balance Scorecard, supply and demand of the sustainable tourism model, and Systems Dynamic model for Risk Analyst as one key analysis for the Information security plan. Would you please give me your important opinions about these topic?

Best Regards,
Francisco

Statistics : Posted by Francisco Villacís • on Thu Jun 24, 2010 6:34 pm • Replies 2 • Views 506

swinging SD !

12720 — 2010-06-28T02:21:48-04:00

Hello all,

I've just read an exciting book from O'Neil, "The Ghosts fo Harlem", in which can be seen some patterns explaining the decline of the Harlem Jazz clubs in the 40's (WW2, drugs usage, end of prohibition, etc.). I have definitely the feeling this could be illustrated with a SD study (typically stocks & flows problematic), and I've started working on this.
As I'm not an experienced SD practicioner, I don't want to do this wrong and spoil this very interesting subject... so I would like like to know if someone from the SD community, fond of jazz like me, would be interested on working on this topic with me, just for the pleasure to think of jazz in a SD context (or vice versa!)...

Looking forward for your answer !

Michel
PhD Sutdent

Statistics : Posted by Michel Lutz • on Mon Jun 28, 2010 1:21 am • Replies 0 • Views 203

Re: Urban development

3408 — 2010-06-22T15:20:59-04:00

Thanks Tom,

I've downloaded the model, but still have to get the books (and also work them through)!

Martin

Statistics : Posted by Martin Schaffernicht • on Mon Jun 21, 2010 8:45 pm • Replies 2 • Views 652

Re: Model building in pair-programming mode

8781 — 2010-06-10T20:42:53-04:00

Hi Len,

Thanks a lot for the info on the tool on group dynamics. Will get deeper into that and learn more

Best regards, Ralf

Statistics : Posted by Ralf Lippold • on Wed Apr 28, 2010 5:17 pm • Replies 13 • Views 7888

Climate Change/Global Warming

2116 — 2010-06-10T15:09:48-04:00

Andrew Freedman wrote in theWashington Post a review to an interesting new book by Naomi Oreskes and Erik M. Conway, called “Merchants of Doubt.” Here’s an excerpt from thePost :

“Through the use of original documents and other source material, Oreskes and Conway trace the history of organized scientific disinformation campaigns back to the 1950s. Although the book does not focus solely on climate change, it is highly relevant to anyone who follows the climate issue, from avid consumers of climate information to casual observers. The book demonstrates what many commentators, such as myself, have stated for years: that attacks on climate science and individual scientists are motivated more by a hostility to the proposed policy solutions to the problem than by clear scientific evidence showing that greenhouse gas emissions do not cause climate change after all.”

Here’s a link to the full story:

Statistics : Posted by Aldo Zagonel • on Thu Jun 10, 2010 2:09 pm • Replies 0 • Views 1320

Re: Carbon neutral: including offsetting fees in registration

2116 — 2010-06-10T14:57:20-04:00

Some of you may be wondering what happened to the carbon neutral proposal that was discussed in the Winter PC Meeting. I copy below a summary offered to the Policy Council which explains why we decided to hold off on the proposal, as well as an external link to the ongoing voluntary offsetting instrument:

"http://www.carbonfund.org/site/pages/land/sds_conference"

If you will be attending the Conference in Seoul, we encourage you to contribute. Contributions last year raised only $651.10 --the equivalent of ~43 participants (at $15.27/each). This is less than 10% of the number of attendees. This year, the estimated average emission per attendee went up and the corresponding contribution was set to $19.55/person (to offset 1.95 metric tons/person). The overall aim is to offset 742.9 metric tons, by raising just over $7,000 in total.

While we may wish to continue the carbon offsets...

Statistics : Posted by Aldo Zagonel • on Sun Nov 29, 2009 12:42 pm • Replies 13 • Views 6931

Re: question on the "ball" choice model

5993 — 2010-06-05T10:09:07-04:00

Thanks for the reference Tom, I'll be sure to check it out. I agree that statistical view certainly has relevance to the overall question of choice, but less so if we are interested in dynamics of choice specifically. The statistical principles are pretty well understood but in most decisions even simple principles tend to be ignored. Example: people often estimate the likelihood of single outcome without giving thought the whole distributions of outcomes. That is technically a no-no (no-no being a technical term for mistake) but as common as grass.

But it's kind of my job to try to promote better analysis and decision processes; the rough part is understanding the dynamics of human choice, and trying to develop processes that are most likely to optimize outcomes.

Statistics : Posted by Michael Fletcher • on Thu Jun 03, 2010 3:39 pm • Replies 2 • Views 1034

Re: Wild guesstimate of the # of SD/ST projects completed

5463 — 2010-05-27T07:41:40-04:00

Hi Jim,

I am not sure that most projects are ever really completed, except to the extent that the people doing a project move on to other things. The important thing from my mind is actually what they leave behind. So I would ask two questions, how many individuals and organizations have been touched by system dynamics, and how many have substatively changed the way they behave as a consequence.

I do think you are right that the first of these is a large number. The Limits to Growth probably remains the biggest contributor, followed by The Fifth Discipline and Urban Dynamics (these may not be right, but they are what come to mind). Jay has recently advocated getting more of this kind of thinking and work into the public eye, and I do think that makes sense.

Thinking of project not as the people touched, but as the work done, it is still a pretty big number. Looking conference proceedings there are lots and lots of different problems that have been worked on, and clearly not ever...

Statistics : Posted by Robert Eberlein • on Tue May 25, 2010 12:58 pm • Replies 3 • Views 1116

Re: Targeting computer languages?

11808 — 2010-05-26T04:30:14-04:00

Travis,

Unfortunately, Java, C and JavaScript are not supported directly by Aivika. Usually, this is not a problem on Windows. At the same time you can use Mono (http://mono-project.com/) on Linux/Unix (including Mac OS X) but the speed of simulation for DES and agents is higher (sometimes significantly) under .NET as my tests show.

Java is a special case. It is possible to port the module of System Dynamics to Scala. It must be straightforward enough. But Aivika essentially simplifies a modeling for DES and agents using so called computation expressions (a syntactic sugar for monads and monoids). In my opinion it is so crucial that I don’t know how to replace them in Scala.

Regarding the visual modeling, Aivika has a slightly different goal. It’s mainly a library for creating .NET and Silverlight applications and fast prototyping of complex (probably, hybrid) models.

Thanks
David

Statistics : Posted by David Sorokin • on Tue May 25, 2010 9:42 am • Replies 1 • Views 999

Re: Limits to Growth

2116 — 2010-05-25T22:41:07-04:00

For those interested in this discussion stream, Jørgen Stig Nørgård, John Peet, and Kristín Vala Ragnarsdóttir, published an informed and thoughtful short-article, online, about "The History of the Limits to Growth": "http://www.thesolutionsjournal.com/node/569"

Statistics : Posted by Aldo Zagonel • on Mon Jan 25, 2010 3:52 pm • Replies 8 • Views 2267

Re: Dynamical systems and system dynamics models

7885 — 2010-05-25T17:01:58-04:00

>>I am wondering about the relationship between "dynamical systems" and "system dynamics models". The >>latter describe "feedback-driven" systems. If the "dynamical" essence of a system is generated inside the >>system (otherwise, would it be a system at all?), then I'm tempted to think that any "dynamical system" >>can be described as a "feedback-driven" system and thus represented by a "system dynamics model".

I’m an engineer who has some experience on both “dynamical system” and “System Dynamics.” Mathematically speaking, “dynamical system” and “System Dynamics” are identical, “ordinary differential equations (ODE)”. In engineering disciplines, “system dynamics” and “dynamic systems” are used interchangeably. Stock and flow are called “state” and “derivative” in ODE, respectively.

Even though they are mathematically identical, I see “gigantic...

Statistics : Posted by Sangdon Lee • on Tue May 18, 2010 9:28 am • Replies 10 • Views 2652

Re: Seoul solidarity

5058 — 2010-05-25T09:42:14-04:00

These last years, I cannot find anymore the name of the people on the conference photos. When I look at the Oxford conference for example, most photos have the names of the people written below them. For those who cannot attend the conference it is nice to look at the photos, but knowing who is being photographed would be a great plus. Maybe there is some way to know about the names that I did not find. Can anyone tell me where to find the names? Sometimes joining some explanations with a photo is as important as the photo itself.
Jean-Jacques Laublé

Statistics : Posted by Jean-Jacques Lauble • on Fri Apr 30, 2010 10:32 am • Replies 2 • Views 1070

Re: Birds nest diagrams as a symptom of the need for SD

5610 — 2010-05-24T04:53:42-04:00

Thanks JJ.

It appears, then, that German comedy is, well, not very funny!

Statistics : Posted by Lee Jones • on Tue Apr 27, 2010 7:23 am • Replies 16 • Views 2744

Prison Dynamics - Dennis Meadows

11279 — 2010-05-20T01:12:35-04:00

Does anyone have a copy of the paper Dennis Meadows presented in 2007 called "Dynamics of Growth in the New Hampshire Prison Population" -- only the Abstract is linked online and the internet has not given up any other links.....

Statistics : Posted by Eric Stiens • on Thu May 20, 2010 12:12 am • Replies 0 • Views 1476

Re: SD in commercial project planning tool

9235 — 2010-05-17T21:41:40-04:00

pmBLOX was just quoted in a blog on CIO.com. Here is the link:
"http://advice.cio.com/jim_vaughan/10320/project_managers_need_to_keep_it_simple?page=1"

Statistics : Posted by J. Chris White • on Sat Apr 03, 2010 1:02 am • Replies 1 • Views 1037

Re: SD course pre tests?

3671 — 2010-05-15T22:45:02-04:00

> ...testing students at the start and again at the end of the course to see how their views of systems, feedback and system dynamics has changed...
< My dissertation investigates how and under what conditionsclients learn to solve problems in system dynamics consulting engagements and suggests something very similar. The purpose is for the reflective practitioner to have a means of assessing the extent to which clients learn fundamentals of system dynamics and how the clients assess the result(s) of intervention. My thesis includes a semi-structured interview template to measure client learning, and the case analyses report the results. I currently use a variant to measure learning in my SD project work.

George Richardson used (and may still use) a much more rigorous assessment with his students than I suggest. I don't have a proper citation but he did publish on the topic, perhaps in SDR? But I don't remember a follow-up article in which he mentions...

Statistics : Posted by James Thompson • on Wed May 12, 2010 9:46 am • Replies 3 • Views 1097

Socio Environmental Resarch

5452 — 2010-05-04T12:32:05-04:00

I was reading an interesting book and wondered if others have seen it as it is a bit off our normal topics.

This is Peter Taylor's 2005,Unruly complexity : ecology, interpretation, engagement (from University of Chicago Press). This is much less about ecological modeling and very much more about the ecological modelers themselves and the philosophy, anthropology, and politics of modeling. It complements Richardson's 1991,Feedback thought in social science and systems theory (University of Pennsylvania Press) by providing a some interesting insights into various "threads" of ecological modeling (although I am not sure ecological modelers would agree with all of Taylor's insights) . System dynamicists will be interested in the detailed discussion regarding Tony Picardi's 1975 MIT dissertationA Systems Analysis of Pastoralism in the West African Sahel .

Apologies if you have already seen this...

Statistics : Posted by Richard Dudley • on Tue May 04, 2010 11:32 am • Replies 0 • Views 1398

Re: Word3 Model

12509 — 2010-04-29T14:37:16-04:00

Thomas, thank you for offering me the information. It helps me a lot.

Scott, thank you for your suggestion and I am looking into that book.

Statistics : Posted by Yilin Zhuang • on Fri Apr 23, 2010 12:18 pm • Replies 3 • Views 945

Strogatz on integrals

5515 — 2010-04-27T12:27:38-04:00

Steven Strogatz has a neat article on integration in the NYT, "http://opinionator.blogs.nytimes.com/2010/04/18/it-slices-it-dices/" (Follow the link on his name to other interesting companion articles.)

These conceptual roadblocks stumped the world’s finest mathematicians for the next 19 centuries … until Gregory, Barrow, Newton and Leibniz established what’s now known as the Fundamental Theorem of Calculus in the mid-1600s. The Fundamental Theorem is a powerful link between integrals and the subject of last week’s column, derivatives. It greatly expands the universe of integrals that can be solved, and it reduces their calculation to grunt work. Nowadays computers can be programmed to use it — and so can students. With its help, even the stovepipe problem that was once a world-class challenge now becomes an exercise within common reach. (For the details of Archimedes’s approach

...

Statistics : Posted by Thomas Fiddaman • on Tue Apr 27, 2010 11:27 am • Replies 0 • Views 1413

Click to jump to page…

Page 1 of 4 • 1, 2, 3, 4