Augusto Carena asks:
>
>Why - if true - System Dynamics, in nearly four decades, did not exploit
>(both in universities and in business) all the enormous potential that
many acknowledge and we practitioners feel? Is this a local problem (we
work in Italy) or a more generalized one?
>
>
>If you think that this matter is appropriate to the list, and yet
>presents unexplored aspects, Id like to propose it as subject of
>discussion; otherwise Ill be grateful to receive any information to
>fill this lack.
I also do not know the extent to which this question has been explored.
However, I feel that this question is not only relevant, I think it is THE
question!
After auditing a 3-qtr course from Wayne Wakeland at Portland State
University, I felt like I had discovered an enormously valuable technique.
It seemed as though my colleagues could hardly fail to see this as well.
It is now almost 10 years later, and I remain baffled at the tremendous
hurdles that appear to be in place.
Here are some of them:
1. Although powerful, DYNAMO was not easy to use. This is not a comment
on the developers, but on the state of the art at the time. Diagrams
occurred on paper, and then required coding, proofreading, etc. Compile
errors were common, and jobs were run in batches, precluding immediate
feedback.
2. STELLA, and friendlier (and cheaper) desktop computers eliminated many
of these problems. The diagrams and the equations are closely tied
together, and simulation runs can be conducted immediately.
3. After several years using STELLA I found it enormously difficult to
document my work. I would find myself with a deskful of printouts, but I
had to laboriously label each one as it was printed, or I would forget the
values of the parameters. These were very simple models; impossible with
more complex models.
4. When I found a particularly interesting run, I would save it as
Pharmacokin 1.7. Another interesting run would be Pharmacokin 1.8, etc
etc.
Two weeks later Id open a folder and find a long list of saved models.
Which was which? It would take HOURS to sort this out.
5. I would tell a colleague about some interesting work, and want to show
him or her the results. But I had no viable document. I had Pharmacokin
1.7, 1.8 ....
"Come in and look at my computer (when we both have time......). Not likely.
6. As a result I developed a set of templates, and found a good screen
capture shareware program. Together I call these "Instant Manual". I now
run Word and STELLA side by side.
It is possible to (a) think out loud, documenting ones current
conceptual framework in text, (b) create a simple model structure, capture
and paste it into Word, (c) capture and paste the equations, (d) document
the setting of parameters (including dt!), (e) run the simulation, (f)
capture the output graph, and add a caption, (g) capture the table and add
a caption, and so on.
Now, since I document the equations, and all parameter changes, I no longer
have to save v. 1.7, 1.8, 1.9, etc. I just pull the parameters out of the
written document. I can show this document to my colleagues, students,
etc.
I find this to be a tremendous advantage, and I believe is an important
factor in the development of CC-STADUS curriculum materials (and SyM Bowl).
Many of the documents disseminated by the Creative Learning Exchange are
in this format.
By logging ones own work, and by communicating the work, SD proceeds more
quicky.
Wayne W stated recently that he no longer does -any- modeling in the
absence of Instant Manual. When he does, he finds to work largely
evaporated a week or so later. He also estimates that 75% of his work is
in Word, 25% in STELLA. That says a lot about the modeling process
itself.
Advertisement: These templates took very many hours to develop. I could
give this away, but Id prefer to distribute it as share-ware ($25), and
use the $$ to support SyM Bowl
7. In biomedical work there is a strong aversion to quantitative analysis
of systems, because of pre-conceived notions regarding the math
requirements.
8. SD requires disciplined thinking. Many people dont want to do this.
9. Jay Forrester and others have noted that SD provides strategic
advantages in business. Therefore, those that have discovered this have a
great incentive NOT to tell others about it. We have seen evidence of this
in recent; members are quite rightly reluctant to discuss clients work in
too much detail. I cant comment on this personally, but would like to
hear other opinions on this point. It sounds reasonable to me.
If and when SD becomes wide spread in biomedical work, this should not be a
problem. We have an incentive to TELL people about our work, not hide it.
FANATACISM:
In Concord in July 94 Peter Senge cautioned against fanaticism. He defined
(roughly) a fanatic as someone who rigidly clings to an idea, and who was
unwilling to critically evaluate this idea, and unwilling to recognize or
acknowledge its limitations. This should be contrasted to an evangelist.
(See Guy Kawasakis book)
To the extent that we discuss these issues here, I guess it would be hard
to call us fanatics. There is no lack of critical evaluation!
ed
gallaher@teleport.com
,