Ventana software support forum

Posted by ""Jack Homer"" <jhomer@comcast.net> More grist for Kim Warren's mill regarding society strategy development: One thing that I believe has not come up in the discussion so far is the question of our true current status as a field. If we're talking about visions and goals...

Posted by ""Jack Homer"" <jhomer@comcast.net> Jim Thompson writes: ""Environmental science, climatology, population studies, atmospheric sciences and associated fields already use 'dynamic systems' logic. From a gloss of the literature in those fields, the rigour applie...

Posted by ""Jack Homer"" <jhomer@comcast.net> Kirandeep, My doctoral thesis at MIT presents a general theory of the emergence (adoption, modification, evolving use) of a new medical technology, including detailed application to cardiac pacemakers and the antibiotic drug clindamyc...

Posted by ""Jack Homer"" <jhomer@comcast.net> Christina Spencer says: > I agree that it is perfectly reasonable that people with questions that > may have come up before should investigate before posting old questions Let me state again that I haven't asked newbies to investigate...

Posted by ""Jack Homer"" <jhomer@comcast.net> Kim Warren writes: ""I'd just ask, though, that we not discourage people from resurrecting old questions [and answers]."" People should be encouraged to ask any question they want, and novices will, of course, end ...

Posted by ""Jack Homer"" <jhomer@comcast.net> Jay Forrest writes: ""Discussions with clients who have used SD suggest to me that a significant portion of their failure to pursue SD over time is that they tend to find SD answers don't work over time - which is ultimately...

Posted by ""Jack Homer"" <jhomer@comcast.net> Re: modeling problems rather than systems. I have been a little dismayed to see extended discussion of yet another question that was answered in our field decades ago; see, for example, Industrial Dynamics (JWF, 1961), section 5.1, pa...

Posted by ""Jack Homer"" <jhomer@comcast.net> In regard to the definition of stocks, Jack Harich says: > That such contentious principles have not been nailed down would seem to > be an indicator of how young the field of system dynamics remains. This is a much more a reflection ...

Posted by ""Jack Homer"" <jhomer@comcast.net> Jack Harich writes: > Page 86 of Sterman says ""Formulate a dynamic hypothesis that explains > the dynamics as endogenous consequences of the feedback structure."" > This implies that the definition of ""...

Posted by ""Jack Homer"" <jhomer@comcast.net> Now that Jack Harich has clarified that he's looking for ""the key elements of the model [or, better, the real world or the problematic system] that cause it to behave the way it does"", I think we have an answer f...

Posted by ""Jack Homer"" <jhomer@comcast.net> I don't see how Jack Harich's emphasis on root causes is helpful. Trying to find the ""true"" original or root causes in complex social systems (unlike engineered systems) is a fruitless endeavor, because when it c...

Posted by ""Jack Homer"" <jhomer@comcast.net> Tom Forest's idea for minimum requirements for conference papers is interesting and could offer some needed guidance for reviewers. But, I think we'd have to exempt purely methodological (non-applied) papers from those requirements. F...

Posted by ""Jack Homer"" <jhomer@comcast.net> Kim Warren cites Geoff Coyle: "".. A model should do what the real world does, and for the same reasons."" That's still not quite enough. The SD approach to model evaluation (as in Forrester and Senge 1980) also co...

Posted by ""Jack Homer"" <jhomer@comcast.net> John Gunkler writes: >I wish there were a better way in SD modeling to show how one policy (rate >equation) can become a different one. We could then have models that >adapted to, or learned from, their environments. While I can think...

Posted by ""Jack Homer"" <jhomer@comcast.net> Kim Warren writes: > I can't speak for how consultants in general approach the challenge of > embarking on data collection, but have come across everything from [a] > ""give us everything you have got, and we will see what i...

Posted by ""Jack Homer"" <jhomer@comcast.net> Richard Stevenson writes (SD6544): ""In a sense, this process summarises a paradox and an implicit problem of SD - despite considerable achievements in education and academia, it just cannot make a significant impact in the ...

Posted by ""Jack Homer"" <jhomer@comcast.net> Jay Forrester asks: ""Can someone supply some examples of where the way of computing age in a stock will alter the direction of policy recommendations to improve the behavior of a system?"" My doctoral thesis in 19...

Posted by ""Jack Homer"" <jhomer@comcast.net> Tom Fiddaman writes: ""If you play with this, you'll find the expected steady state response. Replacing stuff_in with a pulse, a ramp, and exponential growth is interesting. It becomes apparent that for particular inputs, it...

Posted by ""Jack Homer"" <jhomer@comcast.net> Calculating average age of material in a stock is a special case of calculating any average attribute of a stock, for which the solution is a co-flow structure. See Sterman, Business Dynamics, Chapter 12. The incoming attribute in thi...

Posted by ""Jack Homer"" <jhomer@comcast.net> There is a long history of SD modeling applications to questions of workload management for students and workers of all types. In addition to what you will find in the SD Bibliography under worker burnout and also under service qualit...

Posted by ""Jack Homer"" <jhomer@comcast.net> The idea that the field has been growing at a rate of 10-20% per year sounded like an old estimate to me, so I decided to look at some actual data. Thanks to Roberta Spencer for the raw data; any errors in calculation of average growt...