The qualitative vs quantitative variables discussion has been
extremely valuable. In this context the paper by Conrad
Nuthmann, "Using Human Judgment in System Dynamics Models
of Social Systems", System Dynamics Review, Vol 10, No 1,
would seem to be essential reading for practitioners.
Keith Linard
From: "Keith Linard" <KTL@ce-nwgw.ce.adfa.edu.au>
Keith Linard
Senior Lecturer, University of New South Wales (ADFA)
Director, UNSW Centre for Business Dynamics & Knowledge Management
Qualitative Variables and Mapping of ideas
-
"Keith Linard"
- Junior Member
- Posts: 2
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-
"geoff coyle"
- Senior Member
- Posts: 94
- Joined: Fri Mar 29, 2002 3:39 am
Qualitative Variables and Mapping of ideas
Keith,
Yes, it is very worthwhile as a caution against what Im increasingly seeing
as the risk of recklessness in modelling.
Another VERY valuable source is two papers by Wes Churchman on the false
assumptions in operational research. They were originally in Journal of the
Operational Research Society, Vol. 30, Numbers 2 and 3 but have been
reprinted as part of the OR Societys golden jubilee and have been included
with the latest issue of JORS.
Geoff
From: "Geoff Coyle" <Geoff.Coyle@btinternet.com>
Yes, it is very worthwhile as a caution against what Im increasingly seeing
as the risk of recklessness in modelling.
Another VERY valuable source is two papers by Wes Churchman on the false
assumptions in operational research. They were originally in Journal of the
Operational Research Society, Vol. 30, Numbers 2 and 3 but have been
reprinted as part of the OR Societys golden jubilee and have been included
with the latest issue of JORS.
Geoff
From: "Geoff Coyle" <Geoff.Coyle@btinternet.com>
-
"geoff coyle"
- Senior Member
- Posts: 94
- Joined: Fri Mar 29, 2002 3:39 am
Qualitative Variables and Mapping of ideas
Folks,
Heres a small further contribution to the qualitative versus quantitative
debate.
Some of you may remember C P Snow (later Lord Snow). For those who do not,
he came from humble origins, read physics at Cambridge and (despite that
handicap) went on to become very great and very good in the British
establishment. He is famous for a lecture he gave in about 1959 in which he
bemoaned the emergence of two cultures - roughly scientific and liberal
arts - each of which expressed important aspects of the human condition but
neither of which understood, nor cared to understand, the other.
During and after a very distinguished career in the civil service he became
a novelist with a series called Strangers and Brothers in which he traces
the life of a semi-autobiographical character. These are, unfortunately, no
longer much read but they have always fascinated me so I read them from time
to time. Yesterday I was re-reading the eponymous novel of the series in
which one of the characters makes the following remarkable statement:
"What a wonderful invention a map is. Geography would be incomprehensible
without maps. Theyve reduced a jumble of facts into something you can read
at a glance. Now I suspect that economics is fundamentally no more difficult
than geography. Except that its about things in motion. If only someone
could invent a dynamic map."
Bear in mind that this was published in 1940!
It seems to me that this is what the qualitative phase of SD does for
problems with both soft and hard variables, and that makes SD into an
amazing
discipline. I know of no other operations research method which even comes
close.
However, a geographical map is drawn using clear and accepted conventions.
We seem to have evolved three variants: Stock/flow diagrams, CLDs, and
Influence diagrams. I wouldnt die in a ditch over which is used except
that, for me , SF diagrams are cumbersome to draw and CLDs typically involve
a smallish number of variables (there is no reason why that has to be so but
its typical of practice) and dont distinguish between physical effects
and those of information flow and management action. An ID does make that
distinction where it is useful to do so and can be drawn with larger numbers
of variables - 50 or 60 is not uncommon (there are numerous examples in my
books and papers and in the writings of others, notably Eric Wolstenholme).
I am, however, VERY clear in my mind on two points.
The first is that mapping is an intellectual exercise which has to be done
with pencil and paper. I have, to my horror, seen someone trying to draw an
ID directly into a graphics package. The role of software is to record
thought not to support it and that person predictably got a bad result
because he was wasting his brain time in clicking on icons and dragging them
about, not on understanding a problem. (Im not going to be PC and write she
when the person in question was male).
The second is that a map puts onto ONE piece of paper a model of the
geography drawn to a useful scale. A good IDs main strength (and this is
also true of a good CLD or SF) is a portrayal of complex problem. That
accomplishment is of inestimable practical value so my question in the
debate is to ask for demonstration of the added value of quantification in
cases where, as I have tried to explain, there may be serious uncertainties
in data and causal mechanisms.
This second, one piece of paper, argument makes we worry about cases I have
seen in which people try to understand and explain a model by taping
together 10 or 15 sheets of SF diagram as printed out by a graphics package.
Yes, I KNOW that some of the packages have a tunnel-down feature to produce
aggregated SF diagrams but that, of course, is not the same as the full
diagram and conceals much.
Well, there it is, but C P Snow still gets my vote as a wise old bird.
Weve also had some chat about scales and Jay suggested how one might define
a scale for integrity. That intrigued me and I found two slightly different
dictionary definitions of the term. One mentions moral principles, the other
honesty, and both have the idea of upright behaviour. Of course, these are
all rather imprecise and I wonder if two or more people would have the same
understanding of integrity, even if they shared a common cultural
background. If they had different backgrounds they might have very divergent
ideas of what adhering to moral principles might mean. Suppose, however,
that 5 people knew that Smith (whom they all know) was a 3 on Jays scale
and Brown (also well known) was an 8 and that they agreed, roughly, with
that. They are now asked to position Jones on that scale. I suspect that the
best they would do is to agree on where Jones lies relative to Smith and
Brown but with no more than better/worse/in between precision. Suppose they
agree on in between, but I seriously doubt that they would all agree that
Jones is a 5 and there would be some degree of dispersion between, perhaps,
4 and 6. Thus, while one can certainly make up a scale for anything you
choose, the meaning of that scale (what is Integrity?), its calibration (do
we all agree on Smith and Browns positions) and its practical use (where is
Jones to be located) are all FRAUGHT with grave uncertainty. Does anyone
know what the psychometric literature says about this sort of thing, as Jay
and I seem to be doing an awful lot of guesswork and assertion.
Someone mentioned doctors asking about pain on a scale from 1 to 10 (in
fact, it would have to be zero for a complete absence of pain). I asked a
few doctors I know all of whom said they would never waste time on such a
silly (their words) question. The reason is plain. Zero means something but
what is 10? The same as the pain from a broken leg? Ive never had one so I
dont know. The pain of childbirth? Im unlikely to know that! In any case,
childbirth varies enormously from case to case, or so I understand.
In short, these qualitative scales seem to me to require to be used with
very great care. Software will accept anything; the question is whether it
means anything when youve programmed it and whether the results take you
very far, or even take you in the wrong direction.
Regards,
Geoff
Professor R G Coyle,
Consultant in System Dynamics and Strategic Modelling,
Telephone +44 (0) 1793 782817, Fax ... 783188
email geoff.coyle@btinternet.com
Heres a small further contribution to the qualitative versus quantitative
debate.
Some of you may remember C P Snow (later Lord Snow). For those who do not,
he came from humble origins, read physics at Cambridge and (despite that
handicap) went on to become very great and very good in the British
establishment. He is famous for a lecture he gave in about 1959 in which he
bemoaned the emergence of two cultures - roughly scientific and liberal
arts - each of which expressed important aspects of the human condition but
neither of which understood, nor cared to understand, the other.
During and after a very distinguished career in the civil service he became
a novelist with a series called Strangers and Brothers in which he traces
the life of a semi-autobiographical character. These are, unfortunately, no
longer much read but they have always fascinated me so I read them from time
to time. Yesterday I was re-reading the eponymous novel of the series in
which one of the characters makes the following remarkable statement:
"What a wonderful invention a map is. Geography would be incomprehensible
without maps. Theyve reduced a jumble of facts into something you can read
at a glance. Now I suspect that economics is fundamentally no more difficult
than geography. Except that its about things in motion. If only someone
could invent a dynamic map."
Bear in mind that this was published in 1940!
It seems to me that this is what the qualitative phase of SD does for
problems with both soft and hard variables, and that makes SD into an
amazing
discipline. I know of no other operations research method which even comes
close.
However, a geographical map is drawn using clear and accepted conventions.
We seem to have evolved three variants: Stock/flow diagrams, CLDs, and
Influence diagrams. I wouldnt die in a ditch over which is used except
that, for me , SF diagrams are cumbersome to draw and CLDs typically involve
a smallish number of variables (there is no reason why that has to be so but
its typical of practice) and dont distinguish between physical effects
and those of information flow and management action. An ID does make that
distinction where it is useful to do so and can be drawn with larger numbers
of variables - 50 or 60 is not uncommon (there are numerous examples in my
books and papers and in the writings of others, notably Eric Wolstenholme).
I am, however, VERY clear in my mind on two points.
The first is that mapping is an intellectual exercise which has to be done
with pencil and paper. I have, to my horror, seen someone trying to draw an
ID directly into a graphics package. The role of software is to record
thought not to support it and that person predictably got a bad result
because he was wasting his brain time in clicking on icons and dragging them
about, not on understanding a problem. (Im not going to be PC and write she
when the person in question was male).
The second is that a map puts onto ONE piece of paper a model of the
geography drawn to a useful scale. A good IDs main strength (and this is
also true of a good CLD or SF) is a portrayal of complex problem. That
accomplishment is of inestimable practical value so my question in the
debate is to ask for demonstration of the added value of quantification in
cases where, as I have tried to explain, there may be serious uncertainties
in data and causal mechanisms.
This second, one piece of paper, argument makes we worry about cases I have
seen in which people try to understand and explain a model by taping
together 10 or 15 sheets of SF diagram as printed out by a graphics package.
Yes, I KNOW that some of the packages have a tunnel-down feature to produce
aggregated SF diagrams but that, of course, is not the same as the full
diagram and conceals much.
Well, there it is, but C P Snow still gets my vote as a wise old bird.
Weve also had some chat about scales and Jay suggested how one might define
a scale for integrity. That intrigued me and I found two slightly different
dictionary definitions of the term. One mentions moral principles, the other
honesty, and both have the idea of upright behaviour. Of course, these are
all rather imprecise and I wonder if two or more people would have the same
understanding of integrity, even if they shared a common cultural
background. If they had different backgrounds they might have very divergent
ideas of what adhering to moral principles might mean. Suppose, however,
that 5 people knew that Smith (whom they all know) was a 3 on Jays scale
and Brown (also well known) was an 8 and that they agreed, roughly, with
that. They are now asked to position Jones on that scale. I suspect that the
best they would do is to agree on where Jones lies relative to Smith and
Brown but with no more than better/worse/in between precision. Suppose they
agree on in between, but I seriously doubt that they would all agree that
Jones is a 5 and there would be some degree of dispersion between, perhaps,
4 and 6. Thus, while one can certainly make up a scale for anything you
choose, the meaning of that scale (what is Integrity?), its calibration (do
we all agree on Smith and Browns positions) and its practical use (where is
Jones to be located) are all FRAUGHT with grave uncertainty. Does anyone
know what the psychometric literature says about this sort of thing, as Jay
and I seem to be doing an awful lot of guesswork and assertion.
Someone mentioned doctors asking about pain on a scale from 1 to 10 (in
fact, it would have to be zero for a complete absence of pain). I asked a
few doctors I know all of whom said they would never waste time on such a
silly (their words) question. The reason is plain. Zero means something but
what is 10? The same as the pain from a broken leg? Ive never had one so I
dont know. The pain of childbirth? Im unlikely to know that! In any case,
childbirth varies enormously from case to case, or so I understand.
In short, these qualitative scales seem to me to require to be used with
very great care. Software will accept anything; the question is whether it
means anything when youve programmed it and whether the results take you
very far, or even take you in the wrong direction.
Regards,
Geoff
Professor R G Coyle,
Consultant in System Dynamics and Strategic Modelling,
Telephone +44 (0) 1793 782817, Fax ... 783188
email geoff.coyle@btinternet.com
-
Bill Harris
- Senior Member
- Posts: 75
- Joined: Fri Mar 29, 2002 3:39 am
Qualitative Variables and Mapping of ideas
Geoff Coyle wrote:
<quoting C. P. Snow from 1940:>
> "What a wonderful invention a map is. Geography would be incomprehensible
You touched a synapse. Edward Tufte in his books on communicating with
graphics (especially his first, I seem to recall) uses well-drawn maps
as one of his examples of graphical excellence, compressing much
information into a small space in a usable fashion.
While Im partial to stocks and flows, I havent drawn one Im ready to
send to Tufte to consider for his next book, nor do I remember seeing
one that jumped out like that.
Im not sure its important--I dont know that any entity-relationship
diagrams, for example, would make the cut, but does anyone have any
thoughts about applying Tuftes principles to SD diagrams?
Bill
From: Bill Harris <bill_harris@facilitatedsystems.com>
--
Bill Harris 3217 102nd Place SE
Facilitated Systems Everett, WA 98208 USA
http://facilitatedsystems.com/ phone: +1 425 337-5541
<quoting C. P. Snow from 1940:>
> "What a wonderful invention a map is. Geography would be incomprehensible
You touched a synapse. Edward Tufte in his books on communicating with
graphics (especially his first, I seem to recall) uses well-drawn maps
as one of his examples of graphical excellence, compressing much
information into a small space in a usable fashion.
While Im partial to stocks and flows, I havent drawn one Im ready to
send to Tufte to consider for his next book, nor do I remember seeing
one that jumped out like that.
Im not sure its important--I dont know that any entity-relationship
diagrams, for example, would make the cut, but does anyone have any
thoughts about applying Tuftes principles to SD diagrams?
Bill
From: Bill Harris <bill_harris@facilitatedsystems.com>
--
Bill Harris 3217 102nd Place SE
Facilitated Systems Everett, WA 98208 USA
http://facilitatedsystems.com/ phone: +1 425 337-5541
-
"Nugent, Michael D"
- Junior Member
- Posts: 3
- Joined: Fri Mar 29, 2002 3:39 am
Qualitative Variables and Mapping of ideas
Tufte uses the fairly well known "map" of Napoleans trip to Waterloo and
back as an example of seven variables clearly depicted in a two-dimensional
(flat) space. Some of the methods used in that map could be adapted to CLDs.
For instance, instead of drawing all connecting arrows the same width, you could
make the width of an arrow represent the strength of the association.
Michael D. Nugent, Ph.D.
From: "Nugent, Michael D" <Michael.Nugent@PSS.Boeing.com>
Organization Support
425.234.3326
back as an example of seven variables clearly depicted in a two-dimensional
(flat) space. Some of the methods used in that map could be adapted to CLDs.
For instance, instead of drawing all connecting arrows the same width, you could
make the width of an arrow represent the strength of the association.
Michael D. Nugent, Ph.D.
From: "Nugent, Michael D" <Michael.Nugent@PSS.Boeing.com>
Organization Support
425.234.3326
-
glitzfam@mindspring.com
- Junior Member
- Posts: 4
- Joined: Fri Mar 29, 2002 3:39 am
Qualitative Variables and Mapping of ideas
Bill,
Ive also been to the Tufte seminars and have great respect for his books.
(The first was the best.)
Regarding system dynamics stock and flow diagrams, we worked very hard to
make them accessible to universal audiences in two large modeling projects.
We engaged a professional illustrator (sort of a business "cartoonist"
almost) and talked him through the model. He then produced some drawings,
which we improved upon, of course.
In a sense, these illustrations were one of the most useful parts of the
modeling effort. We produced hundreds of color, large format copies and
used them in small group workshops to educate and get feedback on the
dynamic relationships in the model. The first illustration, we called it
"The Placemat" due to its size, was used in dozens of planning and visioning
exercises for the US Air Force and Air National Guard. The second graphic
was on the dynamics of workforce diversity in the ANG and was used
extensively at the unit and state HQ level to explain the large system
effects of increased diversity. No off-putting math, no learning curve: all
we needed was a facilitator who knew the basic story. All the important
logic was visible to non-SD trained people.
If youre interested, I can send .ppt files of the illustrations. I think
that theyre still on my work computer.
Regards,
Robert J. Glitz, Col, USAF
From: glitzfam@mindspring.com
Ive also been to the Tufte seminars and have great respect for his books.
(The first was the best.)
Regarding system dynamics stock and flow diagrams, we worked very hard to
make them accessible to universal audiences in two large modeling projects.
We engaged a professional illustrator (sort of a business "cartoonist"
almost) and talked him through the model. He then produced some drawings,
which we improved upon, of course.
In a sense, these illustrations were one of the most useful parts of the
modeling effort. We produced hundreds of color, large format copies and
used them in small group workshops to educate and get feedback on the
dynamic relationships in the model. The first illustration, we called it
"The Placemat" due to its size, was used in dozens of planning and visioning
exercises for the US Air Force and Air National Guard. The second graphic
was on the dynamics of workforce diversity in the ANG and was used
extensively at the unit and state HQ level to explain the large system
effects of increased diversity. No off-putting math, no learning curve: all
we needed was a facilitator who knew the basic story. All the important
logic was visible to non-SD trained people.
If youre interested, I can send .ppt files of the illustrations. I think
that theyre still on my work computer.
Regards,
Robert J. Glitz, Col, USAF
From: glitzfam@mindspring.com
-
"Roy H. Aiken"
- Newbie
- Posts: 1
- Joined: Fri Mar 29, 2002 3:39 am
Qualitative Variables and Mapping of ideas
Robert
Our organization "The Land Use Forum" is in the process of conducting a series
of public participation group modeling workshops. The focus is on land use in
Door County Wisconsin and how we might be able to better understand and manage
growth pressures in the region. Im interested in the illustrations and
drawings you have been working with and would appreciate seeing your work. We
will of course be working with dozens of people who have no knowledge of system
dynamics or model building. Another note - we are working with Prescott College
(Prescott AZ) and their Ugrow program being developed in conjunction with NASA.
Prescott College has been developing this project as part of their
"Sustainability and Climate Change" program
Thanks in advance
Roy Aiken
From: "Roy H. Aiken" <raiken@itol.com>
Executive Director
Door County Land Use Forum, Inc.
5689 Gordon Rd
Sturgeon Bay, WI 54235
920-743-3020
Our organization "The Land Use Forum" is in the process of conducting a series
of public participation group modeling workshops. The focus is on land use in
Door County Wisconsin and how we might be able to better understand and manage
growth pressures in the region. Im interested in the illustrations and
drawings you have been working with and would appreciate seeing your work. We
will of course be working with dozens of people who have no knowledge of system
dynamics or model building. Another note - we are working with Prescott College
(Prescott AZ) and their Ugrow program being developed in conjunction with NASA.
Prescott College has been developing this project as part of their
"Sustainability and Climate Change" program
Thanks in advance
Roy Aiken
From: "Roy H. Aiken" <raiken@itol.com>
Executive Director
Door County Land Use Forum, Inc.
5689 Gordon Rd
Sturgeon Bay, WI 54235
920-743-3020
-
glitzfam@mindspring.com
- Junior Member
- Posts: 4
- Joined: Fri Mar 29, 2002 3:39 am
Qualitative Variables and Mapping of ideas
Greetings to all System Dynamics list members that contacted me concerning the
professional illustrations that we produced to support two large-scale system
dynamics projects.
Due to the large number of people who have requested copies of the illustrations
(over 30 to date) Im working with my contractor to have them posted to their web
site with explanations and maybe copies of the underlying SD models (Powersim).
Ill forward the URL in a message to the listserver when they get it done.
Due to the level of interest, I think that its safe to assume that the issue of
taking the learnings gained from an SD intervention to a larger group concerns many
of us. Both of the SD models to which I referred above were intended to cause
some large-scale "culture change" in our organization. One did better
than the other. In fact, the better model - and diagram - was not the more
successful change artifact. The more lasting project was more successful due
to the advance change management planning that we did (and sold) up front.
Anyway, I hope to send out this URL in the near future and continue the valuable
discussion on using SD for large scale change.
Robert J. Glitz, Col, USAF
HQ USAF Standard Systems Group
Maxwell AFB-Gunter Annex, AL 36114
robert.glitz@gunter.af.mil
professional illustrations that we produced to support two large-scale system
dynamics projects.
Due to the large number of people who have requested copies of the illustrations
(over 30 to date) Im working with my contractor to have them posted to their web
site with explanations and maybe copies of the underlying SD models (Powersim).
Ill forward the URL in a message to the listserver when they get it done.
Due to the level of interest, I think that its safe to assume that the issue of
taking the learnings gained from an SD intervention to a larger group concerns many
of us. Both of the SD models to which I referred above were intended to cause
some large-scale "culture change" in our organization. One did better
than the other. In fact, the better model - and diagram - was not the more
successful change artifact. The more lasting project was more successful due
to the advance change management planning that we did (and sold) up front.
Anyway, I hope to send out this URL in the near future and continue the valuable
discussion on using SD for large scale change.
Robert J. Glitz, Col, USAF
HQ USAF Standard Systems Group
Maxwell AFB-Gunter Annex, AL 36114
robert.glitz@gunter.af.mil