Search found 68 matches
- Tue Nov 29, 2005 12:12 pm
- Forum: SD Mailing List Archive
- Topic: Characterizing System Dynamics
- Replies: 33
- Views: 32176
Characterizing System Dynamics
Posted by =?iso-8859-1?Q?Jean-Jacques_Laubl=E9?= <jean-jacques.lauble@wanadoo.fr> Hi Justin I have a more pragmatic definition of system dynamics: It is a set of equations calculating the values of different variables Xi i = 1. n at different period of time: Xi(t) = Fi (Xj(t),exogenk(t),paraml) j in...
- Sun Nov 27, 2005 2:34 pm
- Forum: SD Mailing List Archive
- Topic: Characterizing System Dynamics
- Replies: 33
- Views: 32176
Characterizing System Dynamics
Posted by =?iso-8859-1?Q?Jean-Jacques_Laubl=E9?= <jean-jacques.lauble@wanadoo.fr> Hi everybody Jim Hines writes < the only defining characteristic of SD work is an interest in how < structure creates behavior. What does creates mean? Does it mean 1.. Has an influence 2.. Has a determinant influence ...
- Sat Nov 19, 2005 12:50 pm
- Forum: SD Mailing List Archive
- Topic: Characterizing System Dynamics
- Replies: 33
- Views: 32176
Characterizing System Dynamics
Posted by =?iso-8859-1?Q?Jean-Jacques_Laubl=E9?= <jean-jacques.lauble@wanadoo.fr> I agree with Finn, but unfortunately finding the causes and the level of their implication is the principal difficulty of SD, and I would say of most of the problems of our world. Give me the way to know the causes of ...
- Sun Oct 16, 2005 1:00 pm
- Forum: SD Mailing List Archive
- Topic: Pre-simulation indicators of usefulness
- Replies: 10
- Views: 8850
Pre-simulation indicators of usefulness
Posted by =?iso-8859-1?Q?Jean-Jacques_Laubl=E9?= <jean-jacques.lauble@wanadoo.fr> Hi Martin I have not the pretensionsness to help you in this difficult matter but your query can still be studied methodically. <We urge SD students to model a problem, not ""the system""; the (ment...
- Wed Oct 12, 2005 11:38 am
- Forum: SD Mailing List Archive
- Topic: Experimental parameter variance
- Replies: 5
- Views: 4971
Experimental parameter variance
Posted by =?iso-8859-1?Q?Jean-Jacques_Laubl=E9?= <jean-jacques.lauble@wanadoo.fr> Hi The high number of parameters is not peculiar to this model. When I built most of my models, I experienced the same kind of difficulty. The influence diagram was easy to build, and looked credible, the equations wer...
- Mon Oct 03, 2005 11:34 am
- Forum: SD Mailing List Archive
- Topic: Experimental parameter variance
- Replies: 5
- Views: 4971
Experimental parameter variance
Posted by =?iso-8859-1?Q?Jean-Jacques_Laubl=E9?= <jean-jacques.lauble@wanadoo.fr> Hello Fadl Some things must be checked. First in the test inputs. I suppose there are several real time series corresponding to several variables of the model in each input test. Have the test inputs the same correspon...
- Sun Sep 18, 2005 12:58 pm
- Forum: SD Mailing List Archive
- Topic: All models are wrong (was Strategy magazine article about Ja
- Replies: 16
- Views: 11356
All models are wrong (was Strategy magazine article about Ja
Posted by =?iso-8859-1?Q?Jean-Jacques_Laubl=E9?= <jean-jacques.lauble@wanadoo.fr> Hi every body. Thank you to all people that answered my question. It gives me a better idea of the intention behind the formula : all models are ... Just two remarks: When I started in the business, being a scientist, ...
- Fri Sep 16, 2005 11:34 am
- Forum: SD Mailing List Archive
- Topic: All models are wrong (was Strategy magazine article about Ja
- Replies: 16
- Views: 11356
All models are wrong (was Strategy magazine article about Ja
Posted by =?iso-8859-1?Q?Jean-Jacques_Laubl=E9?= <jean-jacques.lauble@wanadoo.fr> WAS: REPLY Strategy magazine article about Jay Forrester Hi every body Bruce Skarin writes: < One of the reasons System Dynamics is so unique as an approach to problem < solving is that it recognizes its faults before ...
- Tue Aug 30, 2005 12:16 pm
- Forum: SD Mailing List Archive
- Topic: Interfacing with Excel
- Replies: 7
- Views: 8461
Interfacing with Excel
Posted by =?iso-8859-1?Q?Jean-Jacques_Laubl=E9?= <jean-jacques.lauble@wanadoo.fr> Hi Francisco. I have more or less the same problem. It is like dynamic programming in O.R. One has to take decision every time step. This decision depends on the past events and on future events that are stochastic. So...
- Mon Aug 29, 2005 12:18 pm
- Forum: SD Mailing List Archive
- Topic: Dynamics of Fraud Prevention
- Replies: 4
- Views: 4555
Dynamics of Fraud Prevention
Posted by =?iso-8859-1?Q?Jean-Jacques_Laubl=E9?= <jean-jacques.lauble@wanadoo.fr> Hi John, You can find on the Vensim forum system dynamics subject a simple model that I have starded on the subject. But by lack of time, I have not checked it completely. So it has probably bugs in it, or the equation...
- Sun Aug 14, 2005 1:07 pm
- Forum: SD Mailing List Archive
- Topic: Feedback Thinking for Business? (Was Feedback and Behavior)
- Replies: 8
- Views: 7392
Feedback Thinking for Business?
Posted by =?iso-8859-1?Q?Jean-Jacques_Laubl=E9?= <jean-jacques.lauble@wanadoo.fr> Hi Mark It is just after having worked hard on trying to simulate short term price setting on a model based on days, that I decided to leave it for the moment aside, and explore the alternative of setting up the right ...
- Sun Aug 14, 2005 1:04 pm
- Forum: SD Mailing List Archive
- Topic: Feedback Thinking for Business? (Was Feedback and Behavior)
- Replies: 8
- Views: 7392
Feedback Thinking for Business?
Posted by =?iso-8859-1?Q?Jean-Jacques_Laubl=E9?= <jean-jacques.lauble@wanadoo.fr> Hi Bill You wrote on my remark >> I said that business people understood the concept of feed back, >> but never pretended that they understood their implication, >> particularly when there are many of them. >> We rely ...
- Fri Aug 12, 2005 12:58 pm
- Forum: SD Mailing List Archive
- Topic: Feedback Thinking for Business? (Was Feedback and Behavior)
- Replies: 8
- Views: 7392
Feedback Thinking for Business?
Posted by =?iso-8859-1?Q?Jean-Jacques_Laubl=E9?= <jean-jacques.lauble@wanadoo.fr> Hi everybody At least having not convinced any body I brought some animation to this list, which due to the character of the field is not an easy matter! Now about what I wrote. John Gunkler writes about what I wrote: ...
- Thu Aug 11, 2005 12:49 pm
- Forum: SD Mailing List Archive
- Topic: Feedback and Behavior
- Replies: 24
- Views: 65674
Feedback and Behavior
Posted by =?iso-8859-1?Q?Jean-Jacques_Laubl=E9?= <jean-jacques.lauble@wanadoo.fr> Joel Rahn writes <Jean-Jacques Laublé apparently prefers to use Vensim (which is not the <same as SD) in order not to develop SD models I do not see where I wrote that, I wrote exactly the contrary. I start with a simp...
- Wed Aug 10, 2005 12:20 pm
- Forum: SD Mailing List Archive
- Topic: Feedback Thinking for Business? (Was Feedback and Behavior)
- Replies: 8
- Views: 7392
Feedback Thinking for Business?
Posted by =?iso-8859-1?Q?Jean-Jacques_Laubl=E9?= <jean-jacques.lauble@wanadoo.fr> [ Was Feedback and Behavior (SD5408) ] John Voyer writes > I think the reason is that managers so poorly understand the integration > that goes on in stocks and flows that the resulting dynamics are revealing > to them...
- Tue Aug 09, 2005 11:48 am
- Forum: SD Mailing List Archive
- Topic: Feedback and Behavior
- Replies: 24
- Views: 65674
Feedback and Behavior
Posted by =?iso-8859-1?Q?Jean-Jacques_Laubl=E9?= <jean-jacques.lauble@wanadoo.fr> Hi Foster. When I build a model, I always start with a no stock, no loop model, unless the necessity to have one stock is evident. It looks then like a common influence diagram. It is only driven by exogenous variables...
- Mon May 09, 2005 11:40 am
- Forum: SD Mailing List Archive
- Topic: MRP and Production Planning
- Replies: 12
- Views: 9641
MRP and Production Planning
Posted by =?Windows-1252?Q?Jean-Jacques_Laubl=E9?= <jean-jacques.lauble@wanadoo.fr> Hi Geert Thanks for your references. Two remarks. The particularity of non storability of services works too for some kind of productions: example to order productions. Generally people that work on order, have to wa...
- Sun May 08, 2005 1:16 pm
- Forum: SD Mailing List Archive
- Topic: Service Supply Chains (was MRP and Production Planning)
- Replies: 1
- Views: 3465
Service Supply Chains (was MRP and Production Planning)
Posted by =?iso-8859-1?Q?Jean-Jacques_Laubl=E9?= <jean-jacques.lauble@wanadoo.fr> Hi Ahmet Thanks for replying. You seem to be describing what we call in France a tour operator, who organizes travels, using subcontractors. It does not deliver the service and is more then an pure intermediary as it l...
- Sat May 07, 2005 1:02 pm
- Forum: SD Mailing List Archive
- Topic: MRP and Production Planning
- Replies: 12
- Views: 9641
MRP and Production Planning
Posted by =?iso-8859-1?Q?Jean-Jacques_Laubl=E9?= <jean-jacques.lauble@wanadoo.fr> Francisco I asked a question called 'Aggregation techniques' the 16-1-2005 which summarizes approximately your question. It generated many answers that you can consult on the web site archives of the sd mailing list: h...
- Fri May 06, 2005 1:50 pm
- Forum: SD Mailing List Archive
- Topic: MRP and Production Planning
- Replies: 12
- Views: 9641
MRP and Production Planning
Posted by =?iso-8859-1?Q?Jean-Jacques_Laubl=E9?= <jean-jacques.lauble@wanadoo.fr> Hi Alan You write that there are plenty of models dealing with planning production processes. But unfortunately I never saw any model dealing with planning services where there are no inventories. The main difference b...
- Fri May 06, 2005 1:45 pm
- Forum: SD Mailing List Archive
- Topic: MRP and Production Planning
- Replies: 12
- Views: 9641
MRP and Production Planning
Posted by =?iso-8859-1?Q?Jean-Jacques_Laubl=E9?= <jean-jacques.lauble@wanadoo.fr> Hi Justin. Thanks for answering my e-mail. Can you give some references about your architectures based on resource mapping ideas, like articles, books, software, web site? My principal difficulty but I think it must be...
- Wed May 04, 2005 11:56 am
- Forum: SD Mailing List Archive
- Topic: MRP and Production Planning
- Replies: 12
- Views: 9641
MRP and Production Planning
Posted by =?iso-8859-1?Q?Jean-Jacques_Laubl=E9?= <jean-jacques.lauble@wanadoo.fr> Hi Francisco I have never seen any model or paper dealing with planning and utilization of resources. I have worked for about three years with planning the utilization of our car fleet on a day to basis trying to 'opti...
- Thu Apr 28, 2005 1:07 pm
- Forum: SD Mailing List Archive
- Topic: Shaping the Future" by Popper et al (was Problem Solving ver
- Replies: 17
- Views: 13523
Shaping the Future"" by Popper et al (was Problem Solving ve
Posted by =?iso-8859-1?Q?Jean-Jacques_Laubl=E9?= <jean-jacques.lauble@wanadoo.fr> There is a Web site named http://www.evolvinglogic.com supposed to explain the ideas behind the article in S.A. and that is probably selling something but I do not know what. I tried to understand what is meant by RAP ...
- Fri Apr 22, 2005 12:41 pm
- Forum: SD Mailing List Archive
- Topic: Problem Solving versus Optimization
- Replies: 8
- Views: 7533
Problem Solving versus Optimization
Posted by =?iso-8859-1?Q?Jean-Jacques_Laubl=E9?= <jean-jacques.lauble@wanadoo.fr> Hi Erling. I think that there will never be a definitive answer to your question, because it depends on the problem you are working on. The tendency is always to generalize something that has worked on something to eve...
- Sun Apr 17, 2005 1:57 pm
- Forum: SD Mailing List Archive
- Topic: Causal Loop and Stock-Flow Diagrams
- Replies: 3
- Views: 4785
Causal Loop and Stock-Flow Diagrams
Posted by =?iso-8859-1?Q?Jean-Jacques_Laubl=E9?= <jean-jacques.lauble@wanadoo.fr> Hi There is a paper from the late SD conference in Oxford called Developing system dynamics models from C.L.D. from Thomas Binder If you are a bit accustomed to modern mathematics formulation, it should give you intere...