Search found 31 matches

by Bill Harris
Sun Apr 18, 1999 8:40 am
Forum: SD Mailing List Archive
Topic: Discrete Event Simulation v. System Dynamics
Replies: 13
Views: 10487

Discrete Event Simulation v. System Dynamics

> Which is better depends on the questions that you wish to answer. If you are > worried about manufacturing floor layout, machine scheduling, machine downtown > and the like use discrete modeling. Alternatively, if you want to relate > manufacturing to product development and marketing use SD. > > ...
by Bill Harris
Fri Jul 31, 1998 8:33 am
Forum: SD Mailing List Archive
Topic: Systems from the top?
Replies: 26
Views: 54842

Systems from the top?

George, I like the points, but I have a question. > The consulting industry mantra is "sell at the top." Often SD does not. If A change management course I went through emphasized that by talking about the need for "authorizing sponsors", followed by a cascading chain of "re...
by Bill Harris
Fri Apr 17, 1998 8:31 am
Forum: SD Mailing List Archive
Topic: Some questions Re:accreditation
Replies: 9
Views: 23293

Some questions Re:accreditation

> theory. Ive seen an MIT dissertation from a person whos name always > escapes me (Graham, I think, or was it Greene) which seemed to do in a > quantitative sense what Senges archetypes did in a qualitative sense: give > one some rules of thumb to use in place of detailed simulations. It was > base...
by Bill Harris
Thu Apr 16, 1998 8:34 am
Forum: SD Mailing List Archive
Topic: Some questions Re:accreditation
Replies: 9
Views: 23293

Some questions Re:accreditation

Tom, > scientific method. I actually had in mind a particular case in the SD > literature in which an excellent practitioner made 2 changes simultaneously > in a model, and attributed the outcome to the wrong one. This reminds me of an article I read on proofs in mathematics which pointed out that t...
by Bill Harris
Tue Apr 14, 1998 9:06 am
Forum: SD Mailing List Archive
Topic: Some questions Re:accreditation
Replies: 9
Views: 23293

Some questions Re:accreditation

Tom, I think your ideas of a informal (my word, not yours) code of ethics is a good one. However, > - thou shalt perform parameter change experiments one at a time Doesnt the field of design of experiments teach that factorial designs may be significantly more efficient than changing one parameter a...
by Bill Harris
Thu Apr 09, 1998 8:41 am
Forum: SD Mailing List Archive
Topic: Professional Accreditation
Replies: 15
Views: 30003

Professional Accreditation

Chris Trost wrote: > As a licensed professional engineer and SD practitioner, Im against any > form of professional accreditation for SD consultants! As a former engineer who chose not to seek licensing because it wasnt needed in my field, I resonate quite well with Chriss arguments. I do agree with...
by Bill Harris
Mon Apr 06, 1998 9:04 am
Forum: SD Mailing List Archive
Topic: Systems of problems
Replies: 5
Views: 7788

Systems of problems

George Richardson writes: > Bill asks if we cant model systems, apparently thinking that we can. ^^^^ There are too many of us "Bills" out here!. :-) That was another one. > Im so attached to this notion of problem focus that I cant imagine you > would not agree with it. (Have to admit to ...
by Bill Harris
Wed Apr 30, 1997 9:03 pm
Forum: SD Mailing List Archive
Topic: System Dynamics Models for Education Demand
Replies: 1
Views: 2168

System Dynamics Models for Education Demand

Fred Nickols wrote: >Im thinking about trying to model the "behavior" of my companys business >environment. Specifically, the demand for higher education (the demand for Fred, If Im misreading your intent, then I apologize. One of the things I have read and experienced in what modeling and...
by Bill Harris
Thu Apr 10, 1997 9:29 am
Forum: SD Mailing List Archive
Topic: leverage points
Replies: 29
Views: 64771

leverage points

Bill Braun wrote: > Subject: REPLY leverage points (SD0997) > Can you expand on the Senge thought. Seems, on the surface, to fly in the > face of the influence of underlying structure and to perhaps run afoul of > some archetypes. As I recall (it was about a year ago), he was speaking after the pers...
by Bill Harris
Tue Apr 08, 1997 7:58 am
Forum: SD Mailing List Archive
Topic: leverage points
Replies: 29
Views: 64771

leverage points

Steve Nyland wrote: > Subject: REPLY leverage points (SD0991) > Couldnt help but respond to this one. If theres no commitment from > the top the potential for successful implementation drops > significantly. Reminds me of an old Greek saying....."the fish rots It sounds good. However, I just fi...
by Bill Harris
Mon Apr 07, 1997 8:46 am
Forum: SD Mailing List Archive
Topic: SD vs. Econometrics
Replies: 5
Views: 5107

SD vs. Econometrics

George, Thanks for your _very_ interesting posting! Besides some seemingly impressive data, you included some important philosophical reminders and (for me) new (or newly packaged) insights. > errors for a few of our models, over a ten year period, (sit down at this > point) have typically been in t...
by Bill Harris
Thu Apr 03, 1997 9:33 am
Forum: SD Mailing List Archive
Topic: Differential equations
Replies: 25
Views: 39522

Differential equations

You raise some very interesting points. > Differential equations are difficult, confusing, weak, and > unrealistic. They often mislead students as to the nature of systems. Thanks for saying this. While Ive studied ODEs and PDEs in school and used them some at work, I can remember feeling more comfo...
by Bill Harris
Tue Apr 30, 1996 8:23 pm
Forum: SD Mailing List Archive
Topic: Modeling for PDCA
Replies: 3
Views: 2920

Modeling for PDCA

Benny Budiman writes: >advances in the fields. Many people share hopes that system dynamics >modeling can be used as flight simulators to help turn the PDCA wheel *** >in managing socio-economic systems. Id inject the word faster here (***). Weve used simulation in such systems to great advantage in...
by Bill Harris
Mon Apr 29, 1996 8:37 pm
Forum: SD Mailing List Archive
Topic: Circular Causal Structures
Replies: 1
Views: 2116

Circular Causal Structures

One thought keeps coming back when I think of feed-back/-forward and "circular causal structures" (it says the right thing, but it doesnt yet flow naturally off the tongue :-). Feedback (and feedforward), as I learned about them as a former practicing electrical engineer, both seem to be u...
by Bill Harris
Mon Apr 29, 1996 8:20 pm
Forum: SD Mailing List Archive
Topic: Generic Structures: Hunting the Snark?
Replies: 6
Views: 4561

Generic Structures: Hunting the Snark?

Jim and others talk about a collection of molecules being assembled. Are these available to the general public (yet)? I noticed Jims comment that he was hoping Pal Davidson or his group might put them on the Web, so that seemed to imply that they would become available in the future, but "hope ...
by Bill Harris
Thu Apr 25, 1996 8:36 pm
Forum: SD Mailing List Archive
Topic: A public s/w for SD EGO
Replies: 1
Views: 1808

A public s/w for SD EGO

Gene, Here is the message I got from the developer of EGO when it first came out. Just as a note, Ive found it reasonably easy to use, and I like the fact that it manages causal loop diagrams, unlike iThink (but like PowerSim?). The primary difference Ive found is the lack of emphasis on exogenous v...
by Bill Harris
Tue Apr 23, 1996 1:31 pm
Forum: SD Mailing List Archive
Topic: discrete vs. continuous simulation
Replies: 17
Views: 10560

discrete vs. continuous simulation

Ed Gallaher wrote: >SD modeling was designed primarily for continuous systems. The fact that >discrete toolboxes have been added to STELLA and others bothers me >somewhat. Not because they are incorrect, but Id like to see a *very >simple* software package available, with just the basic elements. St...
by Bill Harris
Sun Apr 14, 1996 9:01 pm
Forum: SD Mailing List Archive
Topic: Documentation standards
Replies: 4
Views: 3615

Documentation standards

Wayne Wakeland wrote: > Heres what I do whenever I work on a model. I have a Word document > open that is based on a template developed by Ed Gallaher called > "Instant Manual." I toggle back and forth between STELLA and Word It seems to me I saw that template on the mailing list previousl...
by Bill Harris
Sun Apr 14, 1996 8:46 pm
Forum: SD Mailing List Archive
Topic: Modeling for Management
Replies: 1
Views: 1907

Modeling for Management

George Richardson wrote: >I do not yet have the final word on the availability of Modelling for >Management in paperback. The publisher intends to send me a blurb to go I got your note the same day my hardback copy arrived! I really like what Ive seen so far; it brings some articles together Ive rea...
by Bill Harris
Thu Apr 04, 1996 2:54 pm
Forum: SD Mailing List Archive
Topic: Beer game
Replies: 4
Views: 3794

Beer game

Jim Hines wrote: >(Are there any other test inputs that have this character? While I havent tried it in a classroom presentation, you could also pick a constant (i.e., no step) input at a level that doesnt match the initial conditions in all of the intermediate levels (that is, have a constant order...
by Bill Harris
Thu Apr 04, 1996 12:16 pm
Forum: SD Mailing List Archive
Topic: Modeling for PDCA
Replies: 3
Views: 2920

Modeling for PDCA

Bob, >Bill, >I read your comment with great interest. Were working with small farmers in >production of sustainable coffee fields in remote Peru. The biggest problem >is getting a handle on how to induce farmers to develop an afinity to the >project... The experiment here is design a system that sub...
by Bill Harris
Wed Apr 03, 1996 4:38 pm
Forum: SD Mailing List Archive
Topic: SD success?
Replies: 32
Views: 17708

SD success?

John brings up an important point: >rate of demand exceeds the growth of capacity. Such a condition cannot >continue for very long, as the growing number of people seeking SD help >and expertise grow frustrated by inadequate access to skilled people and >resources; as the excess demand causes inexpe...
by Bill Harris
Wed Apr 03, 1996 4:30 pm
Forum: SD Mailing List Archive
Topic: SD success?
Replies: 32
Views: 17708

SD success?

Ed writes: >Next month they will be scratching their head and saying, "Boy, if I had >six round holes in the frame of my car, I could put this trailer hitch on >..... " So someone drills the holes for them and they say, "Thanks, I >dont know anything about cars!...." They STILL d...
by Bill Harris
Wed Apr 03, 1996 12:13 pm
Forum: SD Mailing List Archive
Topic: SD success?
Replies: 32
Views: 17708

SD success?

Gene wrote: >than find a need and respond to it with the PC as the answer. Have we >attempted "to Sell" System Dyanmics rather than sell solutions to specific >problems, with System Dyanmics as the vehicle? Are we selling drill bits as >opposed to educating the customer that we have a nift...
by Bill Harris
Tue Apr 02, 1996 8:40 pm
Forum: SD Mailing List Archive
Topic: Questions about application of SD?
Replies: 14
Views: 7522

Questions about application of SD?

Benny, >Has anyone seen similar experience? If so, what should we do to mitigate >the academic smell so that SD can get the senior managaments attention that >it deserves? I had a recent experience that I think was enlightening for me. I was proposing a possible solution to a financial control syste...