April 2000
Date: Mon, 03 Apr 2000
Subject: Re: Suggestion for A Spring Reflection
From: "Tom Oden" <toden@aisj.jhb.school.za>
To: "k-12sd" k-12sd@sysdyn.mit.edu
Thanks for the re-direct.
As a high school principal, I have found that raising awareness about
dialogue skills and conversational modalities is an extremely powerful tool.
Specifically, p.263 of The Fifth Discipline Fieldbook has a set of "Opening
Lines" that I carry around on a clipboard. Since most of my day is spent in
various forms of conversations, I refer to it quite often.
As a former English teacher, I wish I would have had the "lines" to use in
the facilitation of classrooms discussions -- actually, as a means to move
from the paradigm of discussion to a different sort of group inquiry.
Tom Oden
--
High School Principal
American International School of Johannesburg
27-11-464-1505, x207
27-11-464-1327 (FAX)
toden@aisj.jhb.school.za
----------
>From: k-12sd <k-12sd@sysdyn.mit.edu>
>To: k-12sd@sysdyn.mit.edu
>Subject: Suggestion for A Spring Reflection
>Date: Thu, Mar 30, 2000, 9:20 PM
>
> Date: Thu, 30 Mar 2000 13:53:44 -0500
> To: k-12sd@sysdyn.mit.edu
> From: "Timothy Joy" <tjoy@pps.k12.or.us>
> Subject: Re: Suggestion for A Spring Reflection
>
> A pleasant and hopeful spring to all:
>
> At the behest of some colleagues, we approach you with a question.
>
> What we ask here is not for pedagogical musings, but for the keen,
> sharp-edged voice of experience: what have you actually heard and what have
> you actually said. We have among us teachers at many levels working in the
> daily trough--our stock of experience grows daily. What has this taught us?
>
> An April question:
>
> The last month or so we have heard about students and society disconnecting
> from schools. We believe, do we not, that system dynamics transforms
> curricula and puts a powerful tool in students' minds.
>
> Hence, this question: what is your most effective example of a system
> dynamics tool that has rejuvenated or refocused students' attention and
> effort?
>
> Please be specific about the lesson and how students responded.
>
> -----
>
> Nan Lux, Deb Lyneis and Tim Joy
>
Xxxxxxxxx
From: niall.palfreyman@assyst-intl.com
To: k-12sd <k-12sd@sysdyn.mit.edu>
Date: Fri, 31 Mar 2000
Subject: Re: Dicey!
Excuse me? Mammoth Extinction Game? Sounds interesting, but I can't find any
mention of it among the CLE materials.
Niall.
Xxxxxxxx
Date: Mon, 3 Apr 2000
To: k-12sd <k-12sd@sysdyn.mit.edu>
From: Eileen Riley <rileye1@massed.net>
Subject: Re: Suggestion for A Spring Reflection
Thanks to Tom Oden for a very specific systems "tool." I just pulled out
the Fieldbook and copied page 263 for our administrative team meeting
tomorrow. As a School Business Manager, who tries to integrate STITO as
much as possible, who is in the middle of budget season, this was just
great! Thank you.
Eileen Riley
Carlisle Public Schools
Xxxxxxxxxxx
Date: Tue, 04 Apr 2000
To: k-12sd <k-12sd@sysdyn.mit.edu>
From: Marion Turner <mturner@sd70.bc.ca>
Subject: Re: Suggestion for A Spring Reflection
Another tool we have found very useful in our administrator meeting
discussions is the Skilful Discussion material on p 385 of the Fieldbook.
It really increases the power of the discussions and leads to better
decisions.
Marion
Marion Turner
District Principal, Curriculum and Instruction
SD# 70, Alberni
4690 Roger St., Port Alberni, B.C. Canada V9Y 3Z4
Ph: 250.720.2779 Fx: 250.723.2567
Xxxxxxxx
Date: Tue, 04 Apr 2000 22:06:51 -0400
From: Alma Watson <almaw@bellsouth.net>
To: k-12sd <k-12sd@sysdyn.mit.edu>
Subject: Re: Why are kids disconnecting from schools?
I couldn't agree more. Why does the system continue with the dumb
practices. We have know for a long time that success begets success and
that it rewards itself. I knew it as a regular classroom teacher and
now as a special educator. There is nothing that can take the place of
that "I did it" smile. However small the success. How can we be more
effective in turning the tide?
regards, Alma
xxxxxxxxx
Date: Tue, 04 Apr 2000
From: "Allan Collins" <collina@irn.pdx.edu>
To: <k-12sd@sysdyn.mit.edu>
Subject: Discussion Topic
It is great to be part of this wonderful discussion on systems dynamics.
My masters thesis involves looking at a system dynamic curriculum at the
middle school level. I am interested in how using SD as a tool can help in
the transfer of the SD skills to other academic domains.
Some questions:
How have teachers (i.e., teachers using SD in the classroom) combated the
literature on situated cognition (Greeno, 1997)?
Are students exposed to SD across the school curriculum (i.e., history,
English, science, math classess)?
It seems that SD is a "transfer" tool, if students are truly learning to
think in such a way.
I would like to hear from anyone, especially teachers using SD in the
classroom. Does the entire school weave SD into the curriculum or is it a
tool that individual teachers choose to use?
cheers,
Allan Collins
Reference
Greeno J., (1998) The situativity of knowing, learning, and research.
American Psychologist, Jan., 5-25.
Xxxxxxxxxx
From: sthompson@foundation.panasonic.com
To: k-12sd@sysdyn.mit.edu
Date: Wed, 5 Apr 2000
Subject: theory of change
Hello, all -- I was wondering if any of you know of a good article that
introduces the concept of Theories of Change or Theories of Action. I'm
looking for a piece that uses language that is accessible and practical.
If the subject is discussed in the context of K-12 educational change that
would be ideal.
The reason I'm searching for an article along these lines
is that my organization, the Panasonic Foundation, has launched a
Leadership Associates Program for seven of the school districts that we've
formed long-term partnerships with. The four domains of the program's
curriculum are 1) systems thinking and strategic thinking, 2) leading and
managing change, 3) organizational context and culture, and 4)
communications with and engagement of internal and external stakeholders.
Over the course of the school year we hold three three-day institutes for
school system leadership teams and assign readings in preparation for each
of the institutes. (We also do on-site work with the teams between
institutes.) The final institute for this first year will be held in late
June, and we need to introduce the concept of Theories of Change in the
assigned readings prior to that institute. Participants responses to our
readings thus far have been generally positive, except when they have been
too academic and theoretical; hence my emphasis on language that is
accessible and applicable.
Thanks in advance for any suggestions you might provide!
Scott Thompson
Assistant Director
Panasonic Foundation
One Panasonic Way, 1F-5
Secaucus, NJ 07094
201-271-3367
fax: 201-392-4126
Xxxxxxxx
From: "Gordon Kubanek and Carmen Hust" <gordkuba@enoreo.on.ca>
To: "k-12sd" <k-12sd@sysdyn.mit.edu>
Subject: use of SD in schools for allan collins
Date: Thu, 6 Apr 2000
Hi Allan,
I am a Science teacher [chemistry] in Canada who is using SD and systems
thinking in a big way to set the processes for my classroom; very much
building towards a "learning organization" - a la Senge.
NO, there are no other teachers doing it in a big way.
I am trying to slowly spread the virus - when I show other teachers they
are impressed and say they want to do it.. but being "busy" they do very
little.
As they say in Portland, rightly, you have to get the KIDS to sell it - let
them talk - and the other teachers will hear . This does does take a year or
two though... there is no fast way - unless you are the BOSS and have a big
workshop - and even then I doubt it would be a
"sustainable" inititiative .
Just be positive, just DO IT, get the kids happy and excitied, and the rest
will follow.
AS Jay Forrester there is only 1 magic:
PERSISTANCE.
yours,
Gordon
Xxxxxxxxx
From: teresa@northwest.com
Date: Thu, 06 Apr 2000
To: k-12sd <k-12sd@sysdyn.mit.edu>
Subject: Discussion Topic
In response to some of your questions, I think that for most teachers, they
begin using Systems Dynamics as individual teachers until the exposure,
interest, time allocation allows it to spread throughout a school across
the curriculum. I think I could speak for most of us using Systems
Thinking and Systems Dynamics that that is our dream. Yet, it is usually a
long and hard task to get to that point. Fortunately there are some
schools and school districts that have wholeheartedly embraced this as a
valuable learning tool
which has made it easier to promote cross-curricular experiences for students.
Some examples are Catalina Foothills in Arizona, Harvard, and Georgia.
Also, fortunately, these people in these schools have become tremendous
leaders in helping and supporting others to get started. Without them,
teachers new to using ST/SD individually could easily become discouraged.
Xxxxxxxxx
From: "Jim Lunsford" <jiml@cabarrus.k12.nc.us>
To: "k-12sd" <k-12sd@sysdyn.mit.edu>
Subject: theory of change
Date: Thu, 6 Apr 2000
Scott,
Several articles (and one book) you may wish to check out are:
"Why Change is a Conscious Choice?" by Bob Anderson, Eric Klein And Jim
Stuart- Jan./Feb., 2000 issue of The Journal for Quality and Participation
"New Direction in Management: The Art of Using Small Changes for Large
Effects" by Gareth Morgan- Journal of Innovative Management, Fall 1998
"New Rules for the New Economy" by Kevin Kelly- Wired Magazine, September
1997
See work on school change by Dr. David H. Kiel, DPH
Management Consultant
Kiel, Thomas, and Woodward
Chapel Hill, NC
See also "Inventing Better Schools" (book) by Phillip Schlechty- Jossey Bass
Publishers, 1997.
I have found these useful. Hope you do.
Jim Lunsford, Assistant Superintendent
Cabarrus County Schools
660 Concord Parkway
Concord, NC 28027
jiml@cabarrus.k12.nc.us
Xxxxxxxxxx
Date: Thu, 6 Apr 2000
To: k-12sd@sysdyn.mit.edu
From: Lees Stuntz <stuntzln@tiac.net>
Subject: DynamiQueST
Registrations now due for the DynamiQueST exposition.
For more information (details, rubrics, etc.), e-mail Lees Stuntz <stuntzln@tiac.net> or visit <www.trinityvt.edu/waters/dynamiquest.html> or <sysdyn.mit.edu/cle/>.
DynamiQueST
An exposition of student and teacher work
in System Dynamics and Systems Thinking, Grades 5-12
Join us for an exciting, first time ever, fun-filled event.
May 19-20, 2000
Trinity College, Burlington, Vermont
This exposition will be a forum for students to
o Showcase their work
o Share their experiences
o Educate others about their work in Systems Thinking/System Dynamics
The exposition is open to any 5-12 grade student. Students may enter any ST/SD related materials-utilizing any or all of the tools-for evaluation with the appropriate rubrics. Each student who achieves a standard of work in any of the five areas (Behavior over Time Graphs, Causal Loops, Stock-Flow maps, Computer Simulation models and Overall Understanding) will be recognized for meeting the standard. Judges will be working from rubrics that will be available to all teachers and students in the packet of information available in November.
There will also be the opportunity for teachers to share their current work utilizing System Dynamics and Systems Thinking to further understanding.
DynamiQueST will kick off with an evening of getting to know each other and participating in interesting, challenging group activities. Saturday morning, May 20th, there will be a showcase of student and teacher work, followed by optional trips and activities in the Burlington area. Meals and lodging will be provided for nominal cost at Trinity College.
This is a unique learning opportunity for students, parents and teachers. For more information (details, rubrics, etc.), e-mail Lees Stuntz <stuntzln@tiac.net> or visit <www.trinityvt.edu/waters/dynamiquest.html> or <sysdyn.mit.edu/cle/> 15, 1999.
DynamiQueST Committee:
Dan Barcan and Sue Jamback, Chelmsford Public Charter School
Alan Ticotsky and Rob Quaden, Carlisle Public Schools
Larry Weathers and Dick Maki, Harvard Public Schools
Will Costello, Waters Grant Project and Chittenden South School District
Steven Roderick, Lincoln-Sudbury Regional School District
Lees Stuntz and Deb Lyneis, Creative Learning Exchange
Lees N. Stuntz
Creative Learning Exchange Phone- 978-287-0070
1 Keefe Road Fax- 978-287-0080
Acton, MA 01720 e-mail- stuntzln@clexchange.org
http://sysdyn.mit.edu/cle/
Xxxxxxxxx
From: Larreynaga@aol.com
Date: Thu, 6 Apr 2000
Subject: theory of change
To: k-12sd@sysdyn.mit.edu
In a message dated 04/06/2000 1:13:49 PM Eastern Daylight Time,
k-12sd@sysdyn.mit.edu writes:
<< I was wondering if any of you know of a good article that
introduces the concept of Theories of Change or Theories of Action. I'm
looking for a piece that uses language that is accessible and practical. >>
For articles, you might check out Gene Bellinger's web site:
http://www.outsights.com While its not exactly what you're asking about, it
may give you insight.
For book length work, I recommend Visionary Leadership by Robert Dilts.
Bob Kalman
Xxxxxxxxxx
Date: Thu, 06 Apr 2000
From: "Nickols, Fred" <FNickols@ets.org>
Subject: theory of change
To: "'k-12sd'" <k-12sd@sysdyn.mit.edu>
In response to Scott Thompson's request for articles introducing the concept
of Theories of Change or Theories of Action, I can point to one article that
might "answer the mail" so to speak. It's titled "Change Management 101: A
Primer," and it regularly draws compliments from those who read.
You can find it at this URL: http://home.att.net/~nickols/articles.htm
Once there, scroll toward the bottom and look for the article under the Work
and Management heading.
Xxxxxxxx
Date: Thu, 6 Apr 2000
To: k-12sd <k-12sd@sysdyn.mit.edu>
From: Eileen Riley rileye1@massed.net
Subject: Suggestion for A Spring Reflection
Thanks - this too looks like an excellent STITO tool. We have "Systems
Roundtables" which purposefully surface concerns around particular issues;
or act as "training sessions" for BOTG's for staff. This would be a good
thing to review when we get to as they say "protocols for reaching a
decision-mindfully (and graciously).
Regards,
Eileen Riley
Xxxxxxxxx
From: PatZito@aol.com
Date: Sat, 8 Apr 2000 11:21:26 EDT
Subject: theory of change
To: k-12sd@sysdyn.mit.edu
Scott,
One of the models that I use for working with teachers on change is the CBAM
(Concerns-Based Adoption Model) theory from the Southwestern Educ. Dev. Lab.
at the Univ. of Texas at Austin. This theory has been in existence and
researched since the early '70's and is to my mind the very best for K-12
educators. Go to their website at www.sedl.org or call them at 512-476-6861.
You will have to call them to order, so go on-line first to see what you
want, and then call and order. They're good people and prompt with sending
materials.
You will want to order: "Taking Charge of Change" by Hord, Rutherford,
Huling-Austin, & Hall. If you also want to be able to document the change
process, get their catalog which is loaded with great publications.
I've been using the CBAM materials in my work with teachers in Pennsylvania
for the past 5 yrs. It is excellent because it is teacher-centered, focuses
on their concerns, and promotes lasting change, not quick fixes. CBAM is
also compatible with systems thinking. Good luck with your work.
Regards,
Pat
Xxxxxxx
Date: Tue, 11 Apr 2000
To: k-12sd <k-12sd@sysdyn.mit.edu>
From: Lees Stuntz <stuntzln@clexchange.org>
Subject: Re: Mammouth Ext. Game?
That is a reference to:
CC1999-04MammothExtinction The Mammoth Extinction Game. Gene Stamell, A Ticotsky, R Quaden
Prepared with the support of the Gordon Stanley Brown Fund. In this interdisciplinary science, math, and social studies lesson, third graders examine how the wooly mammoth became extinct about 11,000 years ago. With a game and a hands-on model they learn about graphing, probability anda exponential decay in math, and they are intorduced to system dynamics modeling as a useful tool for looking at problems. [Cross Curricular, Math, Science, Social Studies, Dynamic Modeling, Elementary School, Middle School] ($1.00 paper only; $6.00 paper + model on disk)
Available on the Web site sysdyn.mit.edu/cle/
Lees N. Stuntz
Creative Learning Exchange Phone- 978-287-0070
1 Keefe Road Fax- 978-287-0080
Acton, MA 01720 e-mail- stuntzln@clexchange.org
http://sysdyn.mit.edu/cle/
Xxxxxxxxx
Date: Wed, 12 Apr 2000
To: k-12sd@sysdyn.mit.edu
From: Debra Lyneis <LyneisD@clexchange.org>
Subject:
Dear K-12 SD folks,
We'd like to give teachers a chance to share ideas, questions and problems
as they use the tools of system dynamics in their curriculum. Tim brought
up this issue:
"The reason I don't use causal loops to instruct is that their grammar-their
inherent structure>is slippery; there's not enough discipline in how they
work so that I can't reason my way through. I'm usually lost. Not a mental
model, but rather a mental muddle. Stocks and flows, on the other hand,
force me to think with some discipline. And, so, I can understand."
Have other teachers encountered this problem? How have you handled it with
your students?"
Thanks,
Tim Joy and Deb Lyneis
Xxxxxxxxxx
Date: Thu, 13 Apr 2000
From: "Kim Clary" <kclary@roseburg.k12.or.us>
To: <k-12sd@sysdyn.mit.edu>
Subject: anecdotal evidence of SD effect
This anecdote is in the spirit of the spring question, I believe. A recent
issue of our high school newspaper had a 2-page spread dealing with
elections. Among the tidbits on the pages were student responses to the
question, "What is the most important issue?" One of the students enrolled
in our SD class answered that he felt minimum wage was the most important
issue. He was quoted as saying, "If it is increased again, inflation will
rise, increasing the amounts goods cost, which would defeat the purpose of
the wage increase in the first place."
Joe Beatty
Kim Clary
Roseburg High School, Oregon
Xxxxxxx
From: Andy Ford <forda@mail.wsu.edu>
To: "'k-12sd'" <k-12sd@sysdyn.mit.edu>
Subject: Start with the Stocks & Flows
Date: Thu, 13 Apr 2000
This is Andy Ford responding to Tim Joy's observation that it's
easier to start modeling discussions with stocks and flows rather than
causal loop diagrams. He feels the stock and flow diagram enforces some
"discipline" on the discussion. Starting with word and arrow diagrams, on
the other hand, may lead to a "mental muddle rather than a mental model."
My teachers encouraged me to begin with word and arrow diagrams,
and I have followed their advice over many years, both in consulting and in
the classroom. But I have come to agree with Tim's observation. The word
and arrow diagrams are often vague and slippery, so the initial discussions
are confusing. I've noticed that it's easier for almost everyone (me,
students, clients, etc.) to first visualize the stocks and flows. Once we
have a reasonable stock and flow diagram, it's much easier to draw the
causal loop diagram to learn if our first cut at a model has the mix of
positive and negative feedback loops that are needed to give the system its
dynamic behavior.
So I "handle this situation" by doing the stocks and flows first.
But what if we are part of a team that has opted to construct causal loop
diagrams to get discussions underway? One simple aid to add some
"discipline" to the creation of these diagrams is to insist that we include
units of measurement for each variable in the diagram. If we can't think
of the units, the variable shouldn't be in the diagram.
Andy Ford
Program in Environmental Science and Regional Planning
Washington State University
Pullman, WA 99164-4430
USA
Phone: 509 335 7846
Email: FordA@mail.wsu.edu
Website: http://www.wsu.edu/~forda
Xxxxxxxx
Date: Thu, 13 Apr 2000
From: Marion Brady <mbrady@digital.net>
To: k-12sd <k-12sd@sysdyn.mit.edu>
Subject:
- Tim brought up this issue:
>
> "The reason I don't use causal loops to instruct is that their grammar-their
> inherent structure is slippery; there's not enough discipline in how they
> work so that I can't reason my way through....
Are you talking about something like this?
The more she worries, the more she eats.
The more she eats, the fatter she gets.
The fatter she gets, the more she worries.
The more she worries, the more she eats.
The more ...........
Marion
--
SUPRADISCIPLINARY, SEAMLESS CURRICULA
http://digital.net/~mbrady/
xxxxxxx
- Date: Thu, 13 Apr 2000
From: Marion Brady <mbrady@digital.net>
To: k-12sd@sysdyn.mit.edu
- Subject: Trying to Get In Sync
- I've subscribed to this list for quite awhile. However, some of
my posts, not being perceived as quite "on target" for a
systems-oriented listserv, don't make the cut.
Having a long history of interest in this matter (my first formal
shot at trying to help students explore systems dynamics was pretty
extensive (pages 440 to 508 in IDEA AND ACTION IN AMERICAN HISTORY, a
secondary-level textbook I wrote for Prentice-Hall in 1977 that didn't
mesh with that era's "back to basics" movement so didn't sell well), I'm
curious about the reasons why, on this subject, I'm sometimes seen as
over the fence somewhere beyond left field.
In an effort to clarify my thinking, I'd like to lay out a series
of hypotheses and invite them to be shot down:
1. Systems concepts are most powerful and useful when grasped at
their most general level, for the higher the level of generality, the
more phenomena to which the student will see the concept as applicable.
The aim of formal, functional, instruction should therefore be to push
students toward a maximum level of generality
2. All known systems (and subsystem) concepts fall into one of
five very general categories of phenomena. These five are (a) place,
(b) time, (c) actors, (d) action, (e) cause.
3. These five being the most general conceptual level of phenomena
possible, it follows that the "closer" students can get to them, the
more powerful and useful their understanding will be.
Here's an example of (a) above, with "nested" conceptual
subsystems from most to least general:
(a) PLACE
-Environment
-Secondary environment
-Tools
-Tools for transport
-Tools for personal transport
-Automobiles
-Chassis
-Suspension
-Steering
-Rack
-Tie rods
-Castle nuts
4. In the study of systems, of course, the relationship of system
components TO each other, and their interactions WITH each other, is of
greatest importance.
5. As is true with the components of systems, the higher up the
scale of generality is the study of relationships and interactions
between components, the greater the power and usefulness of insights.
6. The aim of formal, functional, instruction should be to
constantly push students as close to (a) thru (e) as possible, both in
identifying system components and exploring their relationships and
interactions.
Marion
--
SUPRADISCIPLINARY, SEAMLESS CURRICULA
http://digital.net/~mbrady/
Xxxxxxxxxxxxxx
From: teresa@northwest.com
Date: Thu, 13 Apr 2000
To: k-12sd <k-12sd@sysdyn.mit.edu>
Subject:
I didn't really use causal loop diagrams in instruction until this
year...because I too had some difficulty understanding them. What helped
me was George Richardson's workshop in Portland last year and reading the
Systems Thinker (when I have time) and going through some their models. I
used simple examples with my students this year sometimes before
introducing a particular STELLA model.
At least with the causal loop diagrams I have used so far with students
they seemed to understand them. At least they gave me lots of great verbal
responses. I did a project for a ST/SD class this last fall and it actually
helped me to organize my thinking better by starting with causal loops.
However, up to now I wouldn't have said that. Thanks for offering a good
question.
- TERESA
Xxxxxxxx
From: niall.palfreyman@assyst-intl.com
To: k-12sd <k-12sd@sysdyn.mit.edu>
Date: Fri, 14 Apr 2000
Subject
Tim Joy said (and Deb Lyneis wrote):
> The reason I don't use causal loops to instruct is that their grammar-their
> inherent structure is slippery; there's not enough discipline in how they
> work so that I can't reason my way through. I'm usually lost. Not a
> mental model, but rather a mental muddle. Stocks and flows, on the other
> hand, force me to think with some discipline. And, so, I can understand."
I first heard of SD in relation to a psychotherapy training I was doing at the
time. On that training they referred to CL diagrams as a means of
problem-solving in personal life issues and as a medium for making sense of a
client's view of the world. At the time I thought the idea was very
interesting,
and that's what led me to follow it up and get involved on this list.
However, no matter how good I found the idea, I still had tremendous
difficulties actually using CL diagrams in practise. Once I had wrestled my way
to a CL diagram, or when I found an appropriate diagram in a book, it was a
miracle of clarity, and of enormous help in crystallising my understanding of
the problem. Yet I repeatedly (and despairingly) found that I could not use
them
myself as a means of working towards an understanding of an issue or problem.
Then I discovered SD flow diagrams. Suddenly the world became clear. They
fitted
in so well with work I'd been doing for years in training problem-oriented
teams
of various kinds. I start with a reference mode (my is-state), add to it a
reference representation of my soll-state (wannabe-state), then look for the
major nouns (stocks) associated with it, then intransitive verbs (behaviour)
then transitive verbs (flows), then adjectives (converters), then more nouns
.... etc. etc. And suddenly I have a flow diagram!
My current position: Use SD flow diagrams to get acquainted with (ie,
understand) a problem and for arriving at a solution. Then turn it into a CL
diagram in order to explain to other non-SD people what I'm talking about.
Essentially the above process is the one I'd been using for years with course
participants before I knew anything about SD, but now that I _do_ know
something
about it, everything falls into place and the process comes far more naturally.
Niall.
Xxxxxxxxxxxxxxxx
From: Sayeh Sadat <Sadat@sina.tums.ac.ir>
To: <k-12sd@sysdyn.mit.edu>
Subject: A question
Date: Sat, 15 Apr 2000
One question I have had in modelling is that:
Should every stock and converter we use when modelling have an actual meaning in the real world?
Or can we create things which are not obviously seen or felt outside?
--Somayeh Sadat
--Student of Industrial Engineering Department of Sharif University of Technology, Tehran
Xxxxxxxxxx
Date: Sat, 15 Apr 2000
From: "RICHARD TURNOCK" <Richard_Turnock@pgn.com>
To: k-12sd@sysdyn.mit.edu
Subject: Baldrige
The Baldrige Criteria define a system for managing an organization.
Does anyone know of a stock and flow model based on the Baldrige Criteria?
(For those unfamiliar with Baldrige: www.quality.nist.gov )
xxxxxxxxxx
Date: Sun, 16 Apr 2000 19:37:43 -0400
To: k-12sd <k-12sd@sysdyn.mit.edu>
From: George Richardson <gpr@csc.albany.edu>
Subject: Re: Trying to Get In Sync
Marion wrote:
> I've subscribed to this list for quite awhile. However, some of
>my posts, not being perceived as quite "on target" for a
>systems-oriented listserv, don't make the cut.
> [...] In an effort to clarify my thinking, I'd like to lay out a series
>of hypotheses and invite them to be shot down:
I don't think any of us would shoot anything down, since everyone who
writes to this list has something to contribute. However, there is a
clue in what you wrote that may account for your feelings. There was
not any evidence of _dynamics_ in your system hierarchy.
System dynamics, and the branch of systems thinking that links to it,
inherently begins with a focus on the way things are moving and
changing over time. It begins with dynamic thinking. In that sense,
system dynamics is quite different from general systems theory, the
classic (static) view of holism, or a number of other systems
methodologies such as Checkland's soft systems methodology (SSM). If
we're not talking about graphs over time, we're not talking about a
dynamic system, and thus we are not linking with the branch of
systems thinking that is the focus of this listserve.
Structural thinking -- which here means thinking in terms of stocks
and flow and feedback loops, not hierarchies -- is our effort to
conceptualize the internal structure of a dynamic system that gives
rise to its behavior over time. That's our goal -- explaining
dynamic behavior endogenously, to the extent that's possible.
Structural thinking without dynamic thinking is not system dynamics.
It may be good, in some important senses, but it's not what system
dynamics folk are about.
Does that help?
..George
-------------------------------------------------------------------------
George P. Richardson G.P.Richardson@Albany.edu
Chair, Dept. of Public Administration and Policy 518-442-5258
Rockefeller College of Public Affairs and Policy 518-442-5298
University at Albany, Albany, NY 12222 http://www.albany.edu/~gpr
-------------------------------------------------------------------------
xxxxxxxxxx
From: Dakar@aol.com
Date: Fri Apr 14 14:36:59 2000
Subject: Re: Trying to Get In Sync
To: k-12sd@sysdyn.mit.edu
Hello Marion,
I personally believe that being in sync is over-rated.
I enjoy the fact that this listserve has observers with a wide variety of
points of approach to SD. I am able to learn from the posts.
That being said, I will offer observations directed at your hypotheses:
> 1. Systems concepts are most powerful and useful when grasped at
> their most general level, for the higher the level of generality, the
> more phenomena to which the student will see the concept as applicable.
> The aim of formal, functional, instruction should therefore be to push
> students toward a maximum level of generality
Actually, having an understanding of a system that is more general could be
less useful in the sense that what I love about SD is the call for causal
models based on REAL interaction mechanics. This forces the modeler to
take a "closer look" at the causal forces in his or her model.
e.g stocks and flow diagrams force the modeler to identify influences on an
effect. To progress toward simulation, a description (or guess) must
quantify the influence.
> 2. All known systems (and subsystem) concepts fall into one of
> five very general categories of phenomena. These five are (a) place,
> (b) time, (c) actors, (d) action, (e) cause.
I guess this may be a useful classification scheme, my interest is in how
"the clock" fits together to work!
> 3. These five being the most general conceptual level of phenomena
> possible, it follows that the "closer" students can get to them, the
> more powerful and useful their understanding will be.
> Here's an example of (a) above, with "nested" conceptual
> subsystems from most to least general:
>
> (a) PLACE
> -Environment
> -Secondary environment
> -Tools
> -Tools for transport
> -Tools for personal transport
> -Automobiles
> -Chassis
> -Suspension
> -Steering
> -Rack
> -Tie rods
> -Castle nuts
>
So is the goal that students know that Castle nuts are involved in
transportation technology? To me, it is fascinating to know that when a
car rounds a turn, the inner wheel must be set at an angle different to
that of the outer front wheel in order for proper tire wear and handling.
The difference in the angle depends on the length and width of the car, and
a predictive relationship can be derived using trig or a careful drawing.
If one is designing a race car from scratch, as my students used to do, the
maximum turn speed can be calculated from these considerations before a
single piece is fabricated! Models can be useful!
> 4. In the study of systems, of course, the relationship of system
> components TO each other, and their interactions WITH each other, is of
> greatest importance.
Yes!!! And these interactions are often NOT the ones that intuition or
"common sense" or "common knowledge" suggests.
> 5. As is true with the components of systems, the higher up the
> scale of generality is the study of relationships and interactions
> between components, the greater the power and usefulness of insights.
An interesting observation. It reminds me of the "template" relationship
mechanisms presented in the Stella manual.
> 6. The aim of formal, functional, instruction should be to
> constantly push students as close to (a) thru (e) as possible, both in
> identifying system components and exploring their relationships and
> interactions.
>
Yes! But unpacking this statement is a handful!
Empowering students with Systems Thinking tools to the degree that they can
identify and sketch out models for analysis (and desire to do so) is a
wonderful endeavor. It is currently made more difficult by push toward
standardized "comprehensive" curriculum.
I enjoyed reading your hypotheses, and I don't think we are that out of
sync. As I said before, I enjoy this variety of comments shared on this
list!
Jay Fogleman
Xxxxxxxxxxx
From: Andy Ford <forda@mail.wsu.edu>
To: "'k-12sd'" <k-12sd@sysdyn.mit.edu>
Subject: Are All Stocks "Real"?
Date: Tue, 18 Apr 2000
Sayeh,
An intriguing question!
Tell us what kind of model you are building that led you to this question.
Andy Ford
Program in Environmental Science and Regional Planning
Washington State University
Pullman, WA 99164-4430
USA
Phone: 509 335 7846
Email: FordA@mail.wsu.edu
Website: http://www.wsu.edu/~forda
Xxxxxxxx
Date: Tue, 18 Apr 2000 15:45:58 -0400
From: Marion Brady <mbrady@digital.net>
To: k-12sd <k-12sd@sysdyn.mit.edu>
Subject: Re: Trying to Get In Sync
From: Marion Brady
Cocoa, FL 32927
mbrady@digital.net
> From: Dakar@aol.com
> Date: Fri Apr 14 14:36:59 2000
> Subject: Re: Trying to Get In Sync
Jay,
Thanks much for the interesting, detailed response.
> I personally believe that being in sync is over-rated. I enjoy the fact that
> this listserve has observers with a wide variety of points of approach
>to SD.
> I am able to learn from the posts.
That's reassuring.
> That being said, I will offer observations directed at your hypotheses:
>
> > 1. Systems concepts are most powerful and useful when grasped at
> > their most general level, for the higher the level of generality, the
> > more phenomena to which the student will see the concept as applicable.
> > The aim of formal, functional, instruction should therefore be to push
> > students toward a maximum level of generality.
>
> Actually, having an understanding of a system that is more general could be
> less useful in the sense that what I love about SD is the call for causal
> models based on REAL interaction mechanics. This forces the modeler to
> take a "closer look" at the causal forces in his or her model.
Well, I like that too, especially when some seemingly insignificant
system
component turns out to have major consequences -- "For want of a nail," etc.
The point I was trying to make was that it's a lot easier to move
from big
to small than from small to big. Grasping the concept "climate" pretty well
forces the kid to think about patterns of temperature, humidity, cloud cover,
rainfall, etc., but the reverse -- beginning with, say, rainfall -- isn't so
true. Interested as I am in the integrated, mutually supportive nature of all
knowledge, I want to do my best to send the kid off with a conceptual framework
that's as comprehensive as possible, trusting that he or she will "adjust it
downward" as the situation requires.
> > 2. All known systems (and subsystem) concepts fall into one of
> > five very general categories of phenomena. These five are (a) place,
> > (b) time, (c) actors, (d) action, (e) cause.
>
> I guess this may be a useful classification scheme, my interest is in how
> "the clock" fits together to work!
Same here.
> > 3. These five being the most general conceptual level of phenomena
> > possible, it follows that the "closer" students can get to them, the
> > more powerful and useful their understanding will be.
> > Here's an example of (a) above, with "nested" conceptual
> > subsystems from most to least general:
> >
> > (a) PLACE
> > -Environment
> > -Secondary environment, etc.
> So is the goal that students know that Castle nuts are involved in
> transportation technology? To me, it is fascinating to know that when a
> car rounds a turn, the inner wheel must be set at an angle different to
> that of the outer front wheel in order for proper tire wear and handling....
A line drawn from the king pin or ball joint to the center of the
rear axle
must pass through the tie rod end? Yes, (whether I'm right or wrong) that's
interesting to me also. No, castle nuts aren't the (only) point. I'm
suggesting
that, in the example above, a change at any level will have systemic
consequences, and that's one level.. The more "levels," the more options.
> > 4. In the study of systems, of course, the relationship of system
> > components TO each other, and their interactions WITH each other, is of
> > greatest importance.
>
> Yes!!! And these interactions are often NOT the ones that intuition or
> "common sense" or "common knowledge" suggests.
Again, yes. .....the relationship of an "O" ring's elasticity and
temperature, the relationship between urban block length and crime
patterns, the
relationship between smoking during pregnancy and early childhood behavior.....
> > 5. As is true with the components of systems, the higher up the
> > scale of generality is the study of relationships and interactions
> > between components, the greater the power and usefulness of insights.
>
> An interesting observation. It reminds me of the "template" relationship
> mechanisms presented in the Stella manual.
OK, again?
> > 6. The aim of formal, functional, instruction should be to
> > constantly push students as close to (a) thru (e) as possible, both in
> > identifying system components and exploring their relationships and
> > interactions.
> Yes! But unpacking this statement is a handful!
I've had pretty good luck with middle school level students and above.
> Empowering students with Systems Thinking tools to the degree that they can
> identify and sketch out models for analysis (and desire to do so) is a
> wonderful endeavor. It is currently made more difficult by push toward
> standardized "comprehensive" curriculum.
It certainly HAS been made more difficult. The Orlando Sentinel is
running
an 8-part series of mine on education reform. Number 3 in the series deals
with
that issue. Maybe I can summarize in another post.
> I enjoyed reading your hypotheses, and I don't think we are that out of
> sync.
That's reassuring. Thanks again.
Marion
--
SUPRADISCIPLINARY, SEAMLESS CURRICULA
http://digital.net/~mbrady/
xxxxxxxx
Date: Tue, 18 Apr 2000 15:37:58 -0400
From: Marion Brady <mbrady@digital.net>
To: k-12sd <k-12sd@sysdyn.mit.edu>
Subject: Re: Trying to Get In Sync
From: Marion Brady
Cocoa, FL
<mbrady@digital.net>
> From: George Richardson <gpr@csc.albany.edu>
> Subject: Re: Trying to Get In Sync
>
> ....I don't think any of us would shoot anything down, since everyone who
> writes to this list has something to contribute. However, there is a
> clue in what you wrote that may account for your feelings. There was
> not any evidence of _dynamics_ in your system hierarchy....
George,
Thanks much for the response.
What I wrote was merely an attempt to lay out "the basics" -- the most
general level of system components. I maintained there are five, that in our
attempt to describe or analyze any phenomena, we locate it in physical space,
assign it time dimensions, identify the relevant actors or objects,
describe the
action, and attribute cause.
Static? Yes.
But as soon as one begins to "play" with these elements, altering one or
another of them, the whole becomes dynamic. If my students apply the five-part
model to, say, (a) their classroom, (b) at a present moment in time, (c) with
themselves as the actors, (d) "looking at themselves looking at
themselves," (e)
because (to vastly oversimplify a social institution) they need a grade for the
class and have to endure to get it, what emerges is a static "snapshot" of a
moment in time.
But they have no difficulty seeing that altering any one of the five
turns
the snapshot into a video illustrating major systemic consequences: (a)
raising or
lowering the classroom temperature or light level, changing the seating
arrangement, altering the size of the room, etc., (b) expanding or
contracting the
time frame, (c) doubling or halving the number of students in the class, (d)
(instead of "looking at themselves looking at themselves") filling out
worksheets,
sleeping, doing calisthenics, or something else, and (e) because the assignment
was inherently intriguing or challenging and therefore intrinsically satisfying
rather than being done to get a grade -- altering any one of these alters the
whole.
In my earlier post, I was merely suggesting that, at the most general
level,
(a)--(e) all humans think systemically (and know intuitively that those
"ordinary"
systems with which they're in daily contact are dynamic). The problem for
general education, as I see it, is to make explicit that which is known
implicitly, then attempt to move understanding of that which is "natural" to
ever-higher levels of sophistication.
The instructional problem with this is the one suggested by the old
saying,
"A fish would be the last to discover water."
Thanks again for the response. I really appreciate it.
Marion
--
SUPRADISCIPLINARY, SEAMLESS CURRICULA
http://digital.net/~mbrady/
xxxxxxxxxxxx
Date: Tue, 18 Apr 2000
From: "J. R. Llanes" <llanes@panam.edu>
Subject: Re: Baldrige
To: k-12sd k-12sd@sysdyn.mit.edu
I once tried to do one for purposes of research, ie. do these criteria matter?
You can find it at:
http://llanes.panam.edu/journal/library/vol1no1/llanesarticle.html
J. R. Llanes
- xxxxxxxxxxxx
From: RamzaRider@aol.com
Date: Thu, 20 Apr 2000
Subject: Re: A question
To: k-12sd@sysdyn.mit.edu
Yes, things like happiness, sadness can be modeled; but onto a higher level
like you said: "not obviously seen or felt outside", I personally think that
if you could identify the item you could create the stock/flow. The only
hard part is to identify.
Jaime Wren, of Sam Barlow High
Xxxxxxxxxxx
Date: Sat, 22 Apr 2000
From: William Costello <WILL@cvumail.cvu.cssd.k12.vt.us>
To: k-12sd@sysdyn.mit.edu
Subject: Tipping Points
Those of you who have worked with us at the Waters Center for System
Dynamics are familiar with the concept of "tipping points", those "little
things that can make a big difference." The concept is also employed in
the modeling training software, MSST (Modeling Systems Self-Taught) (see
http://www.trinityvt.edu/waters). Malcolm Gladwell first proposed the idea
in a short article in the New Yorker magazine. He looked (very
systematically) at the decline in reported crime in NYC. Mr. Gladwell has
expanded his work into an excellent book, "The Tipping Point: How little
Things Can Make a Big Difference", Little, Brown & Company,
ISBN0-316-31696-2.
Although not a system dynamicist, this is a superb system dynamics work!
Gladwell begins by looking at the dynamics of infection and epidemic
spread, generalizes his thinking to "social epidemics", and concludes with
several enlightening case studies. For example, Gladwell describes the
work of Joan Gantz Cooney, who set her sights on infecting 3-5 year olds
with literacy, utilizing television as the "vector", providing a daily 60
minute dose of contagion, called "Sesame Street", and hoping it was enough
to serve as an educational "tipping point"; a tipping point that would give
disadvantaged children a leg up when starting elementary school.
Malcolm Gladwell was a business and science writer at the Washington Post.
He submitted the original "Tipping Point" article to the New Yorker, and
was promptly hired to work there. Enjoy the book*.lots here for us K-12
folks.
Available from amozon.com for $12.48.
Xxxxxxxxx
To: k-12sd <k-12sd@sysdyn.mit.edu>
From: niall.palfreyman@assyst-intl.com
Date: Tue, 25 Apr 2000
Subject: Re: A question
- Hi Sayeh,
Like Andy Ford, I would also be very interested in hearing more about the work
which prompted you to ask this question.
In object-oriented modelling there has been a lot of discussion on the issue of
whether classes in a model should be "real" or not. I guess the concensus there
is that if it is something which logically groups together a well-defined
collection of responsibilities, then it should be modelled as a class (whether
or not it's "real") - it's just that 99 times out of 100 such things do indeed
turn out to be real, even if they're sort of way-out things like "sadness" or
"marriage register". I think my feeling about SD is that I'd be a bit
suspicious
if a stock or flow bore no relation to the real world, since these group
behaviours into logical constellations, but I can well imagine creating a few
"unreal" converters for reasons of, say, efficiency.
Cheers,
Niall.
Xxxxxxxxxxx
From: LucasRPS@aol.com
Date: Tue, 25 Apr 2000
Subject: Re: Thanks for the Resource on Tipping Points
To: k-12sd@sysdyn.mit.edu
- Dear Will,
Thanks for the resource from Malcolm Gladwell. The concept of tipping points
and his book can easily be used to create several lessons with my seventh
grade enrichment class. (Every seventh grader in the school takes the class).
One of our means for assessing our program and work has been - Will middle
school students read the newspaper with a different perspective - seeing
interrelationships, connecting stories, and asking about other information
the reporters should have given? The phrase "tipping points" gives a new
vocabulary term that captures a critical concept in models. The language of
mapping and modeling is at the base of their learning and understanding.
In terms of Sesame Street, there is a article in the upcoming Fifth
Discipline Resource Fieldbook - Schools That Learn, written by Dr. Lewis
Bernstein. The cameo reviews a version of Sesame Street broadcast to Israeli
and Palestinian children to foster an understanding of culture and language.
The show began broadcasting in 1998 and an estimated 70% of the
Palestinian-Israeli children and 60% of the Palestinian children are
watching. The piece reviews how it all came about. A story like this helps
students see practical applications of "tipping points" and opens up
discussion and creative problem solving using technology and media.
Good thoughts -
- Tim
Timothy R. Lucas
Superintendent - Ho-Ho-Kus Public Schools
Ho-Ho-Kus Public, New Jersey
Fifth Discipline Education Fieldbook Project
Xxxxxxxxx
Date: Mon, 24 Apr 2000
From: David Wheat <dwheat@wheatresources.com>
To: k-12sd <k-12sd@sysdyn.mit.edu>
Subject: Re: Tipping Points
Ditto the review of Gladwell's book (which I also got from Amazon.com for about
$10 less than the bookstore in the mall). I'm about halfway through it, and my
only quibble is with his strained "character types" (Connectors, Mavens, and
Salesmen), which may be helpful to the general reader but causes the author to
digress too much from the system dynamics fundamentals (probability of contact
between infected & uninfected, probability of infection given a contact, number
of infecteds & uninfecteds to begin with, etc.) so well expressed in the Waters
Center materials.
In addition to the MSST software, those interested in the application of the
epidemic model should take a look at "Plagues and People: A Curricular
Experiment" prepared by the Waters folks; I've been able to adapt some of that
material and use it as an explanatory tool in the treatment of political and
public policy issues in the community college class I teach. I'm only in the
early stages of exploring its application as a proactive tool in my consulting
(ala the efforts aimed at promoting "good" epidemics), but Gladwell's book will
encourage me to do so.
Xxxxxxxx
Date: Mon, 24 Apr 2000
From: Marion Brady <mbrady@digital.net>
To: k-12sd <k-12sd@sysdyn.mit.edu>
Subject: Re: Trying to Get In Sync
From: Marion Brady
Cocoa, FL
<mbrady@digital.net>
> > ....Empowering students with Systems Thinking tools to the degree that
>they can
> > identify and sketch out models for analysis (and desire to do so) is a
> > wonderful endeavor. It is currently made more difficult by push toward
> > standardized "comprehensive" curriculum.
> It certainly HAS been made more difficult. The Orlando Sentinel is
> running an 8-part series of mine on education reform. Number 3 in the series
> deals with that issue. Maybe I can summarize in another post.....
Easier than that, if you're interested, is simply to click on the
link below,
then on the "Orlando Sentinel" button. The articles will come up as they
appeared
in the newspaper.
It's possible you might even read them locally.
Knight-Ridder/Tribune News
Services contacted me last week about making the articles available to the 600
newspapers with 80 million readers that use their services.
I, of course, weighed their request......about 2 seconds.
Marion
--
SUPRADISCIPLINARY, SEAMLESS CURRICULA
http://digital.net/~mbrady/
xxxxxxxxx
From: Sayeh Sadat <Sadat@sina.tums.ac.ir>
To: <k-12sd@sysdyn.mit.edu>
Subject: Are all stocks real?
Date: Tue, 25 Apr 2000
This is Somayeh Sadat answering to Mr. Andy Ford:
The model that led to this question included some companies in a market. They all have their market shares which determines the demand for their products. Somehow, we want to model how their market share changes over time.
What we ( In our SD class) created was an " Index of Market Share " for each company which determined the marketshare of the companies. This "Index" would change as a result of the difference between the "Desired index" and the "index" within a modified time. And the "Desired Index" would change as a result of the companie's relative price ( comparing the price of the company with the average price of the market) and relative demand. This was the whole idea of our model.
We had some discusions about the "Indec of Market Share" . We wanted to relate it to something in the real world . And this brought up this question in the class that should we try to do so at all (relating the index to something real)? That means should every stock and converter of the model represent something really seen in the world?
--Somayeh Sadat
--A Student of Industrial Engineering at Sharif University of Technology, Tehran, Iran.
Xxxxxxxxx
Date: Tue, 25 Apr 2000
To: k-12sd <k-12sd@sysdyn.mit.edu>
From: Ed Gallaher <gallaher@mail.teleport.com>
Subject: Re: What is a stock?
"Are all stocks 'real'?"
It seems to me that anything that accumulates and decays over time,
anything that is still present if one freezes time and takes a snapshot of
the system, can be justifiably modeled as a stock. Most of these are very
tangible (salmon, money), but some may be less tangible (pain, sadness).
It is common in medicine to ask patients to provide an estimate of pain to
the doctor or nurse.
1 = no pain
10 = most excrutiating pain imaginable
With this simple scale, the patient can provide useful information to the
nurse. e.g. when the pain reaches 4-6 it is time for additional pain
medication. when the level drops to 2-3 the pain medication is doing its
job.
I used this rating scale, along with a SD model of opiate pharmacokinetics,
to manage the pain of a patient after orthopedic surgery. It was VERY
effective.
The model simulated the waxing and waning of the drug following known doses
and dose intervals. The patient reported the pain level as described above.
It soon became possible to link a given drug level with a given pain level.
This made it possible to predict when the next dose should be given, and
how large it should be. It was especially useful in the early morning.
Since larger doses are given at bedtime it becomes necessary to determine
the size and time of the first dose to be given in the morning.
I presented this work to the Society for Computer Simulation several years
ago, and I'd be happy to convert it to a pdf file and send it to those that
may be interested.
Returning to the original question, similar scales are used to monitor
depression and other subjective measures. These scales may not be perfect,
but they are a whole lot better than nothing.
Ed Gallaher
Assoc Prof Behavioral Neuroscience and Physiology-Pharmacology
Oregon Health Sciences University
Portland, OR
Xxxxxxxxx
From: "Joseph Baciewicz" <jbaciewi@nycap.rr.com>
To: <k-12sd@sysdyn.mit.edu>
Subject: Stream Analysis
Date: Thu, 27 Apr 2000
We have been collecting data for several years at a local stream with regards to chemical and biological changes. As we progress we will be creating models of the stream and wonder if any other such projects have been attempted.
We are a team of two that are trying to work sytem dynamics into our system and want to make sure we do a good job. Therefore any pointers would be of great use as we start our journey.
Joseph Baciewicz
Niskayuna Schools
Xxxxxxxxxxxx
From: niall.palfreyman@assyst-intl.com
To: k-12sd <k-12sd@sysdyn.mit.edu>
Date: Fri, 28 Apr 2000
Subject: Re: What is a stock?
Ed Gallaher wrote:
> "Are all stocks 'real'?"
> It seems to me that anything that accumulates and decays over time,
> anything that is still present if one freezes time and takes a snapshot of
> the system, can be justifiably modeled as a stock. Most of these are very
> tangible (salmon, money), but some may be less tangible (pain, sadness).
You seem to be making an equivalence here between 'real' and 'tangible',
Ed. For
me the word 'real' means rather anything which can be expressed as a noun, ie,
which possesses some kind of persistent state over time. Clearly pain and
sadness (or even happiness! :-) have this property, so I have no quarrel with
them as being 'real'.
I don't know to what extent my experience may be transferred to SD, but in
object-oriented modelling things get hairy when I start 'reifying' verbs and
adjectives into nouns. Take a word like 'choosing', for example. If I model it
as a verb then it is something which happens and is then past: it sends the
system into one particular future, but the choosing can still be performed
again, to move into a different future. The future is still wide open.
However I
may make the decision to model 'choosing' as a noun: a 'choice'. This
reification of the act of choosing has certain advantages. I can enter it in a
database, and refer to it later. However its very persistence as an object
carries certain dangers - it becomes for instance very easy to regard the
'choice' as something fixed and irreversible. As in: "This career was my
choice,
and I'm stuck with it." In terms of object-oriented software systems
reification
easily introduces inconsistencies and fragilities into a system as different
system components start to react not to current reality, but rather to a
reified
memory of the past 'choice'.
Is all this in any way relevant to SD modelling? I'm not sure. I take the SD
equivalent of a noun to be a stock. Clearly a stock possesses a milder form of
time-persistence than a software object. As an integrator of flows it possesses
a certain inertia - its state at this instant has a declining, but somewhat
persistent, influence on its state in the future. A flow, on the other
hand, has
no persistent state at all, rather responding to the inputs of the moment. And
it is this distinction which I think may be crucial to the issue of whether
stocks and flows should exist in the real world or not.
Sayeh Sadat wrote:
> We had some discusions about the "Index of Market Share". We wanted to
> relate it to something in the real world.
As I understand your "Index of Market Share", Sayeh, it is an instantaneous
quantity calculated on the basis of other values present at a given instant
- it
has no persistent state. It seems to be a calculational convenience, and as
such
is in my opinion best modelled as a converter. If it were modelled instead as a
stock (ie, if it were made 'real'), then suddenly your calculational
convenience
would be introducing persistent effects into the system. The state of the
system
in the future would be influenced by the vagaries of your particular way of
calculating things, rather than by properties existing 'out there' in the
'real'
world. This is why I say that I would be concerned if stocks did not correspond
to something I could observe in the world being modelled.
I'm sorry this came out a little formal. It was my way of working towards an
understanding of my own thoughts on this matter.
Best wishes,
Niall.
Xxxxxxxxxx
From: "John Gunkler" <jgunkler@sprintmail.com>
To: "k-12sd" <k-12sd@sysdyn.mit.edu>
Subject: Anchored perceptual scales
Date: Fri, 28 Apr 2000
Ed Gallaher writes about success using a perception of pain scale. His
success doesn't surprise me since I have believed for most of my adult life
that "anything that exists, exists in some quantity." That means that
anything that exists can be "quantified" with some degree of certainty --
sometimes very accurately, sometimes only approximately.
In particular, when one is working with human perceptions there is a kind of
quantification that seems to work better than other methods: it is called
"magnitude estimation scaling." Applying it to Ed's pain scale may be
instructive. Ed's pain scale is an example of an "unanchored" scale -- it
contains no reference point which could make it possible to compare one
person's perceptions with another's. (Ed did not explicitly need this
capability in his use, so it didn't matter.)
By contrast, using magnitude estimation scaling, one could recast Ed's scale
by including a single reference point -- say, for example, letting "1" on
the scale equal the pain of a severe headache -- then asking people to put
their current pain level on the scale by comparison with the reference. So,
for example, a patient might say: "Today, my pain is about 1/2 of a severe
headache;" or "It feels like three times as painful as a severe headache."
These two different pain levels would be represented on the scale as 0.5 and
3.0 respectively.
It turns out that people, with a little practice, are pretty good at making
such comparative judgments -- and the more familiar they are with the
referent (or the more recent their experience with it) the better they do.
Such a scale also has the advantage of being a "ratio" scale, meaning that
it is fair to conclude that a pain level of 3.0 is six times as painful as a
level of 0.5. With Ed's original scale, one is not justified in concluding
that a level of 2 is half as painful as a level of 4. [If you don't follow
this, think of the temperature scales we commonly use. To say that 40
degrees F is half as warm as 80 degrees F would mean that 4.44 degrees C is
half as warm as 26.7 degrees C. But that's nonsense because the Fahrenheit
and Celsius scales are not ratio scales.]
John W. Gunkler
jgunkler@sprintmail.com
xxxxxxxxxxx
End of April 2000