Search found 73 matches
- Fri Jan 02, 2004 9:23 am
- Forum: SD Mailing List Archive
- Topic: Models for Winning Business
- Replies: 7
- Views: 9812
Models for Winning Business
>1. establishing and maintaining a preferred supplier position >2. developing a relationship of trust with the customer >3. the offering itself >4. price Congratulations on the contract. All of the above impress me as attractiveness multipliers in their own right in which each of their respective co...
- Sat Nov 29, 2003 2:27 pm
- Forum: SD Mailing List Archive
- Topic: Manufacturing Control Systems
- Replies: 30
- Views: 52678
Manufacturing Control Systems
9 At 12:10 PM 11/27/2003 -0500, you wrote: >The important thing to me is to have a **single** name that contrasts >with the term "discrete event". Calling that other thing "a series of >discrete events" in one case and a "process" in another case doesnt do >it for me. Y...
- Sun Nov 23, 2003 9:35 am
- Forum: SD Mailing List Archive
- Topic: What do you mean by the term mental model?
- Replies: 5
- Views: 13587
What do you mean by the term mental model?
6 At 09:02 AM 11/20/2003 -0500, you wrote: >I would be interested to learn what practitioners of system dynamics mean by >the term mental model. If you refer to a written authority, I would >appreciate learning what your reference source is. Jim, I most commonly refer to information that is filtered...
- Sun Nov 23, 2003 9:29 am
- Forum: SD Mailing List Archive
- Topic: Discrete Event vs. DiffEq Models
- Replies: 4
- Views: 12650
Discrete Event vs. DiffEq Models
5 >My discrete event model took a schedule template as input, replicated every >week for as long as the simulation time horizon. Patients would arrive >according to a Poisson process. Tim, Do you mean the patients actually arrive at the clinic according to a Poisson distribution, or their request fo...
- Wed Jun 11, 2003 5:42 pm
- Forum: SD Mailing List Archive
- Topic: Community Forum
- Replies: 10
- Views: 16847
Community Forum
The original genesis of Rutgers inquiry stemmed from the desire to search through list archives for past posts. What is the overall demand for such searching capabilities? With what frequency is the demand for such searches real? Have you found this a drawback to this list with enough fequency to th...
- Wed May 28, 2003 8:34 am
- Forum: SD Mailing List Archive
- Topic: Traffic jams and congestion
- Replies: 8
- Views: 12080
Traffic jams and congestion
Jim, how would the inventory model play out at an intersection (assume fourway, a crossroads) where the spacing must change in an anticipatory way. For example, in heavy traffic, even though the light is still green, I wait until the car in front of me clears the intersection before entering it (tem...
- Wed May 21, 2003 8:12 am
- Forum: SD Mailing List Archive
- Topic: Community Forum
- Replies: 10
- Views: 16847
Community Forum
Web based discussion boards are relatively inexpensive to operate (scripts can be found in a variety of places for free) and may be the only option for people who do not have direct access to a server where list serv software is running. I suspect those factors mostly explain their proliferation. Fo...
- Fri Apr 25, 2003 7:57 am
- Forum: SD Mailing List Archive
- Topic: Can system dynamics models "learn"
- Replies: 46
- Views: 34003
Can system dynamics models "learn"
I read and understood the original message to ask if the the model itself could learn (and thus change). With that as a reference point, I asked if a model that learns/changes could lose its problem focus. I think what you describe in your example below, Jim, is the learning that emerges from variou...
- Fri Feb 21, 2003 5:09 pm
- Forum: SD Mailing List Archive
- Topic: attractivenss multiplier
- Replies: 6
- Views: 13311
attractivenss multiplier
The best example in practice that I know of is Urban Dynamics, by Jay W. Forrester. It is priceless in its application of the attractiveness multiplier, and quite useful for a host of other reasons as well. A good addition to your library. I consider it a staple in mine. Bill Braun From: Bill Braun ...
- Wed Jul 17, 2002 9:38 am
- Forum: SD Mailing List Archive
- Topic: Negative Stocks
- Replies: 4
- Views: 8599
Negative Stocks
I am starting a model of a large watershed. The question has arisen regarding ponds that go dry (inches of water at pond beds low point = 0) and then become parched below the physical pond bed (e.g., the typical cracking of completely dried mud). Rainfall in this case will not instantly add water to...
- Mon Apr 15, 2002 11:49 am
- Forum: SD Mailing List Archive
- Topic: Modeling Anticipation
- Replies: 8
- Views: 14264
Modeling Anticipation
Assumption: In an SD model (within the context of a policy) past decisions are "made present" through feedback from stocks. The stocks capture the diffusion of decisions over time. The mess that results is the accumulation of the effects of a stream of decisions, i.e., iterations of Decisi...
- Sun Mar 10, 2002 9:00 am
- Forum: SD Mailing List Archive
- Topic: System Dynamics Society Membership
- Replies: 9
- Views: 10813
System Dynamics Society Membership
Arguing For: This could be done quite easily and as a matter of Society policy. Populate the list membership from the Society membership and be done with it. The argument may have merit though I question whether it is here (on the list) that it should be explored. Arguing Against: Delays. Different ...
- Mon Dec 10, 2001 8:09 am
- Forum: SD Mailing List Archive
- Topic: A causes B
- Replies: 14
- Views: 28082
A causes B
I have no training in physics, just an avid interest, reading as much as I can. My (untrained) understanding is that at the particle level there is a tremendous amount of interdependent, interactive causal influence going on, but none of it is "simple" cause and effect (of the A causes B v...
- Sun Dec 09, 2001 9:17 am
- Forum: SD Mailing List Archive
- Topic: Text Based SD software
- Replies: 15
- Views: 21683
Text Based SD software
As Geoff guessed, when one drops an SD object on the desktop using Powersim, it is an "empty vessel". In fact, right at creation time the object contains a question mark to indicate that it does not contain an equation. Further, the model cannot be run with any object that has a question m...
- Tue Nov 20, 2001 9:01 am
- Forum: SD Mailing List Archive
- Topic: Attractiveness Multiplier, who cares?
- Replies: 1
- Views: 9507
Attractiveness Multiplier, who cares?
At 02:50 PM 11/19/2001 -0000, Richard Stevenson wrote, in part: >You may formulate variables like attractiveness in different ways, the >ultimate validity test being that it makes sense to the manager who is going I work with physicians routinely. They have a very healthy respect for data and eviden...
- Tue Nov 20, 2001 8:48 am
- Forum: SD Mailing List Archive
- Topic: A causes B
- Replies: 14
- Views: 28082
A causes B
If A (and only A) does indeed cause B, then every time B occurs, A will be present or will have occurred sometime prior. The longer the delay between A and B, the more tenuous the causal link. There may also be other contributing or non-obvious links. Fire [A] causes Heat . Fire [A] also heats Stone...
- Fri Nov 09, 2001 8:51 am
- Forum: SD Mailing List Archive
- Topic: Attractiveness Multiplier
- Replies: 12
- Views: 33314
Attractiveness Multiplier
For the attractiveness multiplier, are the following valid equations? If there are three variables that determine overall attractiveness, V[1], V[2], and V[3], the attractiveness multiplier equation is V[1] * V[2] * V[3]. Similarly, ten variables would be V[1] * V[2] *...* V[10]. With three variable...
- Thu Nov 01, 2001 8:08 am
- Forum: SD Mailing List Archive
- Topic: Attractiveness Multiplier
- Replies: 12
- Views: 33314
Attractiveness Multiplier
There have been a number of comments about Urban Dynamics (e.g., Sterman, SD3408) and the debated merits and flaws of the model. Is the use of multipliers (UD, Productivity Press, pp. 23-25) still considered a valid approach to represent the dynamics of attractiveness (actual and, with delays, perce...
- Mon Sep 17, 2001 4:04 pm
- Forum: SD Mailing List Archive
- Topic: Evaluating an organizations structure
- Replies: 1
- Views: 14583
Evaluating an organizations structure
If you are looking for resources in addition to SD models, I recommend Richard Dafts book, Organization Theory and Design. It contains a number of models that rely on dependent and independent variables and which are largely oriented to fitting the organization to its external environment as well as...
- Tue Jul 24, 2001 8:26 am
- Forum: SD Mailing List Archive
- Topic: Human Behavior in System Dynamics Models
- Replies: 9
- Views: 11223
Human Behavior in System Dynamics Models
Jacks request for example models prompts me to wonder if weve lost the notion of boundaries. If we are attempting to model the deep roots of human feeling and emotion in the belief that they are the ultimate drivers of behavior, it would seem to be a good time to propose we construct a model of ever...
- Mon Jun 04, 2001 7:58 am
- Forum: SD Mailing List Archive
- Topic: ST & SD in real life
- Replies: 13
- Views: 13340
ST & SD in real life
At 10:08 AM 6/1/01 -0400, Jim Hines wrote, in part: >A more promising route, suggested a few years ago by David Andersen, might >be to certify educational programs, rather than individuals. This seems >MUCH easier to me, and might accomplish 70% or more of the objectives. I concur at the same time I...
- Wed May 23, 2001 7:52 am
- Forum: SD Mailing List Archive
- Topic: Models of Medical Risk / Misadventure
- Replies: 3
- Views: 7822
Models of Medical Risk / Misadventure
While not directly SD related, the November, 1998 (Volume 76) issue of the Milbank Quarterly had a number of articles on quality. The articles are written by some of the authors of the Institute of Medicine report, although I believe this volume predates the IOMs report. Bill Braun From: Bill Braun ...
- Tue May 08, 2001 7:25 am
- Forum: SD Mailing List Archive
- Topic: Discrete Event Simulation (DES) and System Dynamics
- Replies: 1
- Views: 6113
Discrete Event Simulation (DES) and System Dynamics
I offered to post Goeffs paper on my page at school so anyone could
retrieve it direct. If anyone else wants to make a document available this
way send it to me and Ill add it to the page.
The page is at http://www.bw.edu/~wbraun/sysdyn
Bill Braun
From: Bill Braun <medprac@hlthsys.com>
retrieve it direct. If anyone else wants to make a document available this
way send it to me and Ill add it to the page.
The page is at http://www.bw.edu/~wbraun/sysdyn
Bill Braun
From: Bill Braun <medprac@hlthsys.com>
- Tue May 01, 2001 8:06 am
- Forum: SD Mailing List Archive
- Topic: Fast demonstrations of complex behaviour
- Replies: 14
- Views: 18693
Fast demonstrations of complex behaviour
At 10:33 AM 4/30/01 -0400, George Richardson wrote: >Is that the "IT" people are supposed to get from this exercise? And >if thats it, then what do we do with it? Perhaps the value varies with the experience and knowledge of the people engaged in the exercise. I have not tried this exercis...
- Tue Apr 10, 2001 8:39 am
- Forum: SD Mailing List Archive
- Topic: Fast Demonstration of Complex Behavior
- Replies: 6
- Views: 21018
Fast Demonstration of Complex Behavior
The group exercise aimed at positioning everyone to be equidistant from two other people in a group is reminiscent of the "boids" program. The hypothesis of the program was that cohesion in flocks could be explained by three rules: 1) match speed with birds in your neighborhood, 2) maintai...