Ventana software support forum

Tom, I am still skeptical about the need to protect the fields reputation from inexperienced pratitioners. A lack of examples may be the result of a reluctance to share bad news, but a lack of examples is also certainly consistant with no examples. Putting together a widely agreeable accredation pro...

Thanks to J. Chris White for providing a first example of inexperienced use of SD. The request for examples is important because one of the arguments for accredation is that accredation will protect the fields reputation from being sullied by inexperienced people. Chris does provide an example of a ...

Khalid Saeed wrote: > Perhaps we should discuss an accreditation process for the teaching > programs rather than for the individuals. Khalid, that sounds very interesting. I wonder if it would encourage colleges and universities (and other organizations, perhaps) to either (1)offer more courses in s...

Will Glass-Husain points out that you might want to hook up an SD tool to a regular programming environment. In addition to Powersim, Vensim also lets you do this via DDE (like Powersim). Vensim also is available as a DLL, which permits you to create a distributable, standalone program which relies ...

Lou, I am all for a discussion, though Im not sure I favor the proposal. Perhaps, your message will initiate a discussion in this email list in addition to the discussion at the conference. An advantage of a discussion here is that this list goes out to a much wider group than will attend the confer...

Pedro Mendes wrote: > 1. Do you know a paper I can cite expressing opinions similar to Tom > Fiddamans? I certainly agree with Toms assessment of the sorry use thus far of complexity research in talking about management and other human endeavors. There will be a conference in December 98 in England ...

I liked Joe Kilbrides clarification of use of term "optimize". However, I think that we should de-emphasize terms like "optimize" in favor of the terms like "improve". Our best efforts will not result in optimized social systems. We can, however, significanlty improve t...

Concerning John Rodats suggestion for a separate conversation on SD in health care. John, I dont think its a good idea to split the list. If there is a need for a more efficient way of seeing which messages pertain to what topics, perhaps we should move to an internet news group? Regards, Jim Hines ...

There seems to be a fair amount of traffic on this email list.

Are we getting to the point where an threaded internet news group would
decongest our mail boxes and make following discussions easier?

Jim
JimHines@interserv.com

All approaches are special cases of more general approaches. Its critically important to bound an approach in order to accomplish something creative. A good analogy is verbal composition in English. A novel (or a sonnet or a limeric) has rules. The novel is a special case of the general class of all...

A further addendum to Johns note on Helmut Weymar.

Helmut Weymar went into commodities trading following his work at MIT in
system dynamics. He became one of the most successful commodity traders
ever. His sd work on commodities might indeed be worth a look.

Jim Hines
MIT
JimHines@interserv.com

I liked Jay Forrests statement and Toms response. Jay had said that System Dynamics was "more appropriate for understanding patterns of behavior and less appropriate for precise modeling" Tom said this caused him to think about approaches that were more precise than system dynamics. In an ...

This is a reply to Jana R. Saitos query about supply chain modeling. Many people have done modeling for issues in supply-chain management. Its one of the oldest application areas. You might take a look at Jay Forresters Industrial Dynamics (Productivity Press). Chapter 15 is on a Production-distribu...

Regarding Jaideeps and Alexandres postings. What is the value of "adjusting the last bits of some parameter values just to get it right! (while feeling confident in the model structure)"? If, as Alexandre says, its "wasting time" doing it by hand at this stage, its also wasting t...

Concerning modeling survival: Here are a few ways to approximate the situation you describe (if I understand it correctly). 1. You could have an aging chain where each level has two outflows: One is the usual outflow into the next level in the chain. The other is an outflow to a sink (i.e. out of th...

Concerning expectations and extrapolations: John Sterman has an interesting paper on inflation forecasts which takes a look at whether smoothing structures can mimic experts predictions (the answer is yes). The molecules and associated documentation provide explanations of the structures used to rep...

Concerning Phil Odences statement that HPS advocates going straight to the stock and flow representation: Starting with S&F works fine when there is a prominent "main chain". Where there are prominant feedback loops, starting with a CLD seems a more natural first step. I once asked Jay...

Concerning mental models.

The area of symbolic anthropology focuses on what we would call mental
models. (They call it "world view"). A classic is Clifford Geertz
"The Interpretation of Cultures".

Jim Hines
LeapTec and MIT
JimHines@Interserv.Com

This is in reply to Michael Beans query about articles on loop vs. stock and flow diagrams. George Richardson has a good article which is mostly about causl loops, but also mentions stock and flow diagrams. It is: Richardson, George. 1986. "Problems with causal-loop diagrams". System Dynam...

In reply to the question regarding teams, here are my thoughts -- Id like to hear other peoples. For a company team for a system dynamics project, I think its wise to look for 1) People who have a hands on knowledge of the issue area under consideration. You need people who know what the physics of ...

This is in reply to Don Taylors recent posting about confidence bands.

Vensim will produce a pleasing visual display of confidence bands if you
specify the distributions for your uncertainty around parameters.

Jim Hines
LeapTec and MIT
JimHines@interserv.com

Aguirre, Yolanda wrote: > Would a system dynamic model be appropriate to try to grasp the problem > of how much will this product penetrate the market and potential price > scenarios? Absolutely. System dynamics has often been used to explore competitive dynamics including the price, reliability, an...

Concerning SD and education administration:

John Voyer, Libra Professor at the University of Sourthern Maines
School fo Business, has done some modeling of this issue for his
university.

Jim Hines
LeapTec and MIT
jimhines@interserv.com

John Holden wrote: Snip > Perhaps a better post to the list would be for references to Universities or > Departments that offer general course work, specific degrees, or even > certificates (perhaps for individuals, like myself, in degree programs at > other universities) in SD or ST. Any takers? Jo...

Ed, I agree that "High School Stock-and-Flow Diagram Computer Simulation" contest doesnt have much marketing flair. (Incidentally, what little I know about your SyM Bowl sounds terrific and apparently its also good marketing!). How did you describe SyM Bowl? I forget how I first heard abou...