Ventana software support forum

*********************************************************************** Hello. Today the conference schedule for the Quebec 98 - International System Dynamics Conference has been updated. To see the list of plenary and parallel sessions, as well as workshops and all other conference information, ple...

Just a short reply to George and Khalids postings on this subject. First, it is important to note that the traditional method for performing multivariat sensitvity anlysis is to take a model and run it again and again changing each time a specified set of constants (model inputs). This process preci...

Hi Everyone - here are some additional questions Fareen posed that I thought might be of general interest. They relate to policy optimization. > 1 - How different are the optimisation approach relative to the > conventional approach? Policy optimization is just another step in the process. The first...

Hi Fareen, Both optimization and optimisation have a long tradition in system dynamics. It is commonly used in three settings: 1) For model calibration a model is repeatedly simulated in order to adjust parameters. David Peterson has a very nice paper on this in Juergen Randers book Elements of the ...

-------------------- Hi All, Here is the May monthly calender. If you are offering courses that teach system dynamics simulation, or course that are built around a system dynamics simulation model microworld please email me the info (vensim@world.std.com) so I can include it in this posting. You sho...

Hi Everyone Ventana Systems, Inc. is pleased to announce the availability of version 3.0 of Vensim. Vensim 3.0 is available for Windows 95/NT, Windows 3.1, the Macintosh and the Power Macintosh. We have rewritten the user interface to make it easier to get started building models and more efficient ...

Hi Everyone, As you have probably noticed list traffic is up somewhat. We have 930 subscribers now and it is growing slowly but steadily. When you respond to a message on the list please decide whether you want to respond to the whole list, or to the sender of the message. Messages that are simple r...

Hi Everyone, Traffic has been increasing and the membership on the list is now up to 746 people. I thought a couple of reminders about protocol would be useful. First keep messages short. Posted messages travel lots of places and fill up lots of peoples in-boxes. Second, always sign your name and em...

Hello Everyone, I am starting to get queries about why things are so quiet on this list. The list, to the best of my knowledge is not broken. There has, however, been a significant lack of activity. I do not have a good explanation for this lack of activity. In order to generate some discussion, I w...

I think Tony posed a very good question, and I am not the first to respond to it. It is an interesting observation that the first three responses were referrals to literature or other writings. While I think academic discussions are wonderful, it is worth remembering that only a tiny percent (or fra...

Hi All, I have finally put together molecules for the Macintosh (my apologies for the delay). They can be downloaded from http://www.std.com/vensim/molecule.html. Note that if you are using Vensim PLE you will also need to get a new version of this for the molecules to work. If you have any comments...

>From Bob Eberlein (vensim@world.std.com) Hello Everyone, Volume is clearly up on this list and there are several people who have contacted me regarding a digest format for this list. I will be setting this up this week and let you know how to receive it in that format. I am also going to be numberi...

Hello Everyone, When posting messages could everyone please 1. Sign the message including your name and email address. Many people never see who the message is from and reply to goes back to the list. 2. Do not include the content of previous messages. Sometimes a line or two is OK but I have to go ...

The discussion on Archetypes, Causal Loop Diagrams and Stock and Flow Diagrams has been interesting. I have noted a tendency to use cryptic abbreviations and fear that this may make things very hard to understand for many (I confess to having had problems at times). Benny Budimen has brough molecule...

The World3 model, as modified for the book "Beyond the Limits," is now included as part of Vensim PLE which you can download from http://www.std.com/vensim or via ftp www.std.com/Newbury/vensim/download/venple.exe The model equations are available in Vensim format, and you can use the soft...

Hello Everyone, We have previously had some discussion on this list about getting software to do system dynamics off the internet. We have just released a Personal Learning Edition of Vensim that can be freely downloaded (http://www.std.com/vensim). The software is intended for students and others w...

Hello Everyone, The results of the vote are 75 yes for more posting and 8 no (20% response rate roughly). Some of the yeas were reluctant, and I will continute to moderate out flames, junk messages and accidental postings of personal messages. However, if you have something interesting to say to som...

Consider the following classical structure: |---> sales --> revenue --> budget to sales force -| | | |------ sales force <---- target sales force <----| At first glance this appears to be a positive feedback loop. However, depending on the value of such things as the fraction of revenue to sales, wa...

>From John Sterman (jsterman@mit.edu) At the MIT Sloan School of Management one can pursue a Ph.D. in system dynamics; Sloan also offers an MBA degree (Masters of Science in Management). Though this is a professional degree (2 years), and involves taking certain required courses in management, one c...

Dear Subscribers, The system dynamics mailing list now has nearly 500 subscribers. Traffic has been relatively light, and this is partly because I have been fairly narrow minded in my moderation on the list traffic. Nonetheless there are a lot of people who are very interested in what is going on in...

Dear Subscribers, The system dynamics mailing list now has nearly 500 subscribers. Traffic has been relatively light, and this is partly because I have been fairly narrow minded in my moderation on the list traffic. Nonetheless there are a lot of people who are very interested in what is going on in...

The MIT System Dynamics in Education project has established an internet server that will be used, among other things to archive this list. The following gives some details on how that archiving will be done. The server will also be used to allow list members to exchange models over the internet. Th...

The article referred to by Joe is "A System Dynmaics Model of National Cocaine Prevalance" byt Jack Homer, System Dynamics Review Volume 9, Number 1 (1993) pages 49-78. - This is excellent work. Bob Eberlein. From: jk@mcs.com (Joe Kilbride) Subject: Re: Models available?? r glitz wrote: >I...

Here are three brief responses to Alan Coronados query on models of War. -------------------------------------------- There is a model by Khalid Saeed that models revolutions in developing countries. I also two years ago adapted the theories of Barrington Moore in regard to revolutions to system dyn...

I am attaching two more replies on the chaos thread. The discussion on chaos has been interesting and fun to read. However, I think it is important to stress that system dynamics is not a search for chaos! A typical pattern in mathematical modeling is to develop a mathematical model that is shown to...