Ventana software support forum

Posted by <richard.dudley@attglobal.net> I assume you are referring to the pages starting at: http://systemdynamics.org/wiki/index.php/Main_Page I believe that the reasons this wiki is under-used are: 1. In spite of their proponents, wikis are not that easy to edit and contribute to... 2. Potential ...

Posted by <richard.dudley@attglobal.net> Given the current conversation I thought it would be appropriate to repost the link to a paper that I found at this web site: http://www.orie.cornell.edu/orie/people/faculty/profile.cfm?netid=pep4 Title: The Financial Meltdown, How did we get in this mess? by...

Posted by <richard.dudley@attglobal.net> This is a very interesting 383 page book full of graphs and reasoning abo= ut sustainable energy. Emphasis is analysis and understanding based on fact= s rather than opinion and hype. Fairly easy reading but scientific nevertheless w= ith data and careful ana...

Posted by <richard.dudley@attglobal.net> A very interesting article on the financial collapse is available from this Cornell Prof's web site. http://www.orie.cornell.edu/orie/people/faculty/profile.cfm?netid=pep4 Note that one of his fields is ""financial engineering"". Title: Th...

Posted by <richard.dudley@attglobal.net> I am interested in learning more about price setting embedded in models. I sometimes see price setting determined by a price-demand curve and a price - supply curve but these seem to be a bit artificial. In the real world buyers base their willingness to purc...

Posted by <richard.dudley@attglobal.net> ""How is it possible that such an important initiative could be started with apparently no knowledge or involvement from the top people in our community who have worked on this for decades ?!"" Certainly an interesting question, and I find...

Posted by <Richard.Dudley@attglobal.net> It might indeed be worthwhile for readers to review the comments in Forrester's 2007 paper in thinking about the society's strategy. Two responses to that paper, one by Jack Homer and another by Yaman Barlas (both in SDR Winter 2007) also deserve examination....

Posted by <Richard.Dudley@attglobal.net> The XXX list that Kim presents seems to me to be a list of _indicators_ that a field (or profession) is in demand. It does not tell us why it is in demand. An easy way to focus the discussion is to use the 'roadblock' approach, and ask: => Why doesn't system ...

Posted by <Richard.Dudley@attglobal.net> Some of you may be interested in a recent paper in Nature which explains why fishing can cause even more disruption of fish populations than previously thought by creating instability in population dynamics .... causing boom and busts in a fished population i...

Posted by <richard.dudley@attglobal.net> At the 2006 meeting I attended a workshop about a software tool called ""conductor"" that simplifies the construction of large Vensim models from sub-modules developed by different groups. Although I have no immediate plans for using this ...

Posted by <Richard.Dudley@attglobal.net> >> > > Maybe it's more like nouns versus verbs. Variables that are verbs >> > > (rates) have a unit per time period, like persons/year. Nouns have >> > > only I agree with some other views that stocks can certainly have units of Posted by <Richard.Dudley@attg...

Posted by <richard.dudley@attglobal.net> I think that my ""minimum modeling standards"" are less rigorous than most people imagine. What I'm thinking of here is the minimum needed to make a model understandable to others. This does not mean the model is good. It does not mean the...

Posted by <richard.dudley@attglobal.net> This is a follow-up to my original post. I see that the topic has switched from my question about questioning poor models, to a discussion of how we proceed with a good modeling process. Well, that's OK, but it does not really answer my question. There are ma...

Posted by <Richard.Dudley@attglobal.net> There has been some discussion within the System Dynamics Society concerning the quality of modeling and how that might be improved. One of the issues is the ""dumbing down"" of system dynamics modeling to the point where it no longer a va...

Posted by <Richard.Dudley@attglobal.net> The following article may be of interest. It points out the problem of limited understanding of interlinked issues (in this case global warming) and the difficulty of getting across more subtle ideas as to how things really work. I think it is a warning to mo...

Posted by <richard.dudley@attglobal.net> I agree with George's response. But we do see, in some contexts, some backlash to group approaches for problem solving. I don't know that this occurs with SD approaches, but it could. An interesting discussion of this problem with regard to groups formed to s...

Posted by <richard.dudley@attglobal.net> I thank everyone for the responses regarding my ""ensuring the quality of models"" question. However, I still didn't get an answer to what I was asking. Perhaps I was not clear enough, or perhaps there is no clear answer. I am somewhat fam...

Posted by <richard.dudley@attglobal.net> Perhaps my comment was not clearly stated. I was not really thinking about public discussion of models, but internal (within an institution or firm) pre-review of models... Sort of a quality control prior to moving to the next step. The next step may be going...

Posted by <richard.dudley@attglobal.net> Those of you in appropriate institutions my be interested in the following source of research funding. Note that the US Forest Service has been give a significant role. Richard Richard G. Dudley USA - NSF Funding Available : Dynamics of Coupled Natural and Hu...

Posted by <richard.dudley@attglobal.net> Those of you in appropriate institutions my be interested in the following source of research funding. Note that the US Forest Service has been give a significant role. Richard Richard G. Dudley USA - NSF Funding Available : Dynamics of Coupled Natural and Hu...

Posted by <richard.dudley@attglobal.net> Citation: Eysenbach G (2006) Citation Advantage of Open Access Articles. PLoS Biol 4(5): e157 doi:10.1371/journal.pbio.0040157 Those of us who are interested moving toward Open Access publishing (OA) for the SD Society might be interested in the above article...

Posted by <Richard.Dudley@attglobal.net> Regarding Yahoo Groups lists. There is already a System Dynamics list on Yahoo with over 300 members, but it is almost exclusively in INDONESIAN. ;-) Only a few of these members are members of the System Dynamics Society. Even though some of those members als...

Posted by <Richard.Dudley@attglobal.net> I agree with Paul (below). A web only format would draw less participation, I believe. However, the ability to include diagrams within postings would be a plus. Is that possible? Richard Posted by <Richard.Dudley@attglobal.net> posting date Thu, 6 Sep 2007 08...

Posted by <Richard.Dudley@attglobal.net> It would seem surprising that geneticists would be surprised... that genes act in ""systems"". A gene acts under a set of circumstances and those circumstances (certainly within a cell or an organism) are caused by other genes and the envi...

Posted by <richard.dudley@attglobal.net> Yes.... I neglected to mention _why_ I am interested in this question: How can we determine the mean time material remains in a stock? In my particular case I am working on a fishery model. Many fishery models are cohort models, but some are single stock biom...