Ventana software support forum

Posted by =?iso-8859-1?Q?Jean-Jacques_Laubl=E9?= <jean-jacques.lauble@wanadoo.fr> Hi Erling <I am eager to hear if some of you can contribute other reasons not to < ""maximise something"" as the problem statement in SD? In my problems, there is pure static optimization mixed with...

Posted by =?iso-8859-1?Q?Jean-Jacques_Laubl=E9?= <jean-jacques.lauble@wanadoo.fr> Alan Graham writes < Of course, if a modeller is using a phased approach, early simpler models should be showing at least the potential stakes involved in one policy versus another, and thus the benefit of choosing a b...

Posted by =?iso-8859-1?Q?Jean-Jacques_Laubl=E9?= <jean-jacques.lauble@wanadoo.fr> Jim Thompson writes: < System dynamics applications are investments with unknowable paybacks. And later on < That is, should < you rely on your ""judgment and intuition, which frequently lead people < to wron...

Posted by Hi everybody. Due to a reorganisation in my business I have been obliged to reconsider the time spent on my different missions and in particular on SD. I noticed 8 drawbacks with SD, and managed to reduce seven of them but I have still to work on the one I consider as the principal: the di...

Posted by =?iso-8859-1?Q?Jean-Jacques_Laubl=E9?= <jean-jacques.lauble@wanadoo.fr> Hi Louis and everybody <The use of IF Then statements suggested by Jean-Jacques seems more <of a tool of convenience for the elimination of the ratio when it can longer <be explained. If I interpreted Sterman correctly...

Posted by =?iso-8859-1?Q?Jean-Jacques_Laubl=E9?= <jean-jacques.lauble@wanadoo.fr> Hi Richard. Is the ratio used elsewhere in the model? If not, the solution is to formulate this like: ratio = it then else (ratio numerator < numerator limit :and: ratio denominator < denominator limit, value indicatin...

Posted by =?iso-8859-1?Q?Jean-Jacques_Laubl=E9?= <jean-jacques.lauble@wanadoo.fr> Hi Geoff I think that the last part of my last message was not sent. Probably an end of page character in the text when pasting. < I asked a world expert on DCM whether he could recommend anything more < practically re...

Posted by =?iso-8859-1?Q?Jean-Jacques_Laubl=E9?= <jean-jacques.lauble@wanadoo.fr> Hi Geoff < To clarify, the software becomes save disabled at 15 days (our colleagues I may test the software if I have once the time. < Of course I'd be delighted to see it when available. I will send it to you and to ...

Posted by =?iso-8859-1?Q?Jean-Jacques_Laubl=E9?= <jean-jacques.lauble@wanadoo.fr> Geoff McDonnel wrote <THe AnyLogic SD tutorial and Bass diffusion (SD and Agent based AB versions) <examples in the trial download from www.xjtek.com illustrate this. I do not see the interest of studying the Bass diff...

Posted by =?iso-8859-1?Q?Jean-Jacques_Laubl=E9?= <jean-jacques.lauble@wanadoo.fr> Hi John Thank you for answering to my question. <If I understand what you're doing (and I'm still not sure I do), I might <suggest that you first do statistical analyses of your data to discover how <many categories yo...

Posted by =?iso-8859-1?Q?Jean-Jacques_Laubl=E9?= <jean-jacques.lauble@wanadoo.fr> Hi Joel Thank your for your answer. Generally the dynamic of a system can already be studied at a high aggregation level, and going into details does not necessarily add a great deal of value. But in my case, the probl...

Posted by =?iso-8859-1?Q?Jean-Jacques_Laubl=E9?= <jean-jacques.lauble@wanadoo.fr> Hi Geoff and thank you Geoff for your answer. I have consulted the books from Louviere and Train on Amazon. They are very close to my preoccupations. The only problem is with the high density of long formulas mixing th...

Posted by Hi I received a directly sent e-mail, that make me think that I have not well explained the aggregation problem. This is the answer to my question and what I answerd back. First answer: Is this useful? ""To determine whether activities taking place serially can be aggregated, con...

Posted by Hi every body. I am currently working on a model where I need to aggregate the demand of the customers in a minimum of classes while the behaviour of these customers relative to the price is similar. My activity : short term car rental. The criterion of classification is simple: they shoul...

Posted by =?iso-8859-1?Q?Jean-Jacques_Laubl=E9?= <jean-jacques.lauble@wanadoo.fr> -- It seems that the future exists in a superposition of all possibilities, -- until we make a decision, when one of these possibilities is selected. -- And, according to the many-worlds interpretation, the universe br...

Posted by =?iso-8859-1?Q?Jean-Jacques_Laubl=E9?= <jean-jacques.lauble@wanadoo.fr> Hi Kim I tried to send mails with attached files. but it does not work on this list. And the messages were not probably sent too. You can find the files in a winzip .zip file on the http://www.ventanasystems.co.uk/foru...

Posted by =?iso-8859-1?Q?Jean-Jacques_Laubl=E9?= <jean-jacques.lauble@wanadoo.fr> Hi everybody. These debates about effective use of modelling must be as old as the World. One remark that follows the last paragraph of Tom Fiddaman about objective and subjective components to the debate. Whether mode...

Posted by =?iso-8859-1?Q?Jean-Jacques_Laubl=E9?= <jean-jacques.lauble@wanadoo.fr> Hi everybody. Responses to the challenge of dealing with dT with non-technical audiences from Kim Warren. I do not understand the problem of explaining the influence of the time step on results to non SD technician. It...