Posted by ""Jack Harich"" <
register@thwink.org>
> Posted by Jay Forrester <
jforestr@MIT.EDU>
> I see here a wishing for something that has likewise not been achieved
> in any other profession.
Hmmm, there seem to be many fields that reliably solve difficult
problems. Physics, chemistry, biology, electronics, etc.
> A model is a theory of behavior that explains the problem at hand.
> There are no rules for obtaining a theory leading to a Nobel Prize in
> physics that is not ""dependent on the brilliance of the modeler."" In
> a more everyday realm, there is no way to teach engineers to be the
> one to design the most successful airplane. Success in an engineering
> design depends on understanding the underlying concepts. Beyond the
> basics, a successful engineer builds on a basic education and grows
> from repeated apprenticeships, from trial and error, from learning
> from past failures, and being winnowed down from the large number of
> engineering graduates who are not willing, or able, or competent, to
> go through the entire learning process.
""There are no rules for..."" - Agreed. However I did not say ""dependent
on the brilliance of the modeler."" I said ""too dependent on the
brilliance of the modeler."" That statement does not infer that there is
a way ""to teach engineers to be the one to design the most successful
airplane,"" etc.
It seems that what's happening in this discussion, and in related ones
over the past years, is our field has moved from the Model Crisis phase
of the Kuhn Cycle to the Paradigm Revolution phase. Debate concerns what
techniques are best for allowing SD to achieve its potential. This
debate rages back and forth, with various propositions rising and
falling in popularity. The focus sharpens, as in the 50th anniversary
issue of the Review. And then the focus fades, as people realize that
what they were focusing on does not have the answers, or even the right
questions.
Richard's query on minimum acceptable modeling standards is an example
of an attempt to reach agreement on at least one factor that would
become part of the new paradigm. Once we can start to agree on factors
like this, we are nearing the end of the Paradigm Revolution phase. The
next phase is Paradigm Change, which will begin once a comprehensive
paradigm emerges that has the clear potential to take the field of
system dynamics forward, to its full potential.
> In this discussion thread, there have been comments about how most are
> not able to devote time to getting a Ph.D. in system dynamics, as if
> that were enough to guarantee success. A full scale academic program
> in engineering or in medicine is only the beginning of the process of
> becoming a true expert.
> The emphasis in these discussions needs to be less on how to find a
> quick path to successful modeling and much more on how to establish
> educational and apprenticeship programs to train experts.
That proposition is an example of a factor that should be part of the
new paradigm. But is it possible that we are putting the cart before the
horse? Isn't the presence of lots of educational programs evidence they
are in demand? And isn't demand a result of successful application of
SD? So it seems that the absence of educational programs is a coincident
symptom of a deeper cause. What that deeper cause might be is what this
debate might try to discover. What is the root cause of why SD has not
achieved its potential?
>> mature. In particular, SD's foundation lacks a repeatable process.
>> Therefore ""more widespread use"" of existing modeling practices will
>> not lead to SD success.
>>
>
> The foundation is never ""mature"" in the sense that it will not be
> improving,
Agreed. I met mature enough to reliably solve the problems the field faces.
> however, I see in this discussion a failure to recognize and discuss
> the foundations that already exist.
This could be useful. It would help us to catalog the factors that
contribute to the field's success. Which ones are missing? Which are
immature? Which are not as critical as they appear? Out of this analysis
would emerge a candidate new paradigm.
> I hope we will have here a discussion of the presently identified
> foundations, because it appears that many people who consider
> themselves working in system dynamics are no aware of the foundations,
> or, at least, have not internalized them.
I'm probably one of them, since I'm self taught.
> As discussed above, it is extremely over-optimistic to expect that
> there will ever be a repeatable process that leads everyone to create
> fully effective models. We should be looking to the other professions
> for guides to creating successful practitioners--look at how a heart
> surgeon has been trained, look at how an engineer who designs a space
> ship or a chemical refinery or even a successful automobile has been
> moved from novice to expert.
Regarding ""leads everyone"" - Sorry if I didn't express myself clearly.
It's more like we need a repeatable process that leads the field, or the
average modeler who has the basic smarts to be a good modeler, to create
effective models.
""We should be looking to the other professions for guides to creating
successful practitioners"" - Yes. But there seems to be the assumption
that the most important factor is how the practitioners have been
trained. I don't think that's a root cause. It's what we are teaching
them. My hypothesis is we don't yet have what we need to teach
successful practice with SD. If you don't have that, then it doesn't
matter how people are trained. Ploughing more money into more training
will not make a difference.
But we can look to other professions for the strategies they have used
to achieve success. SD is an engineering tool. It's used to solve
problems. How a complex tool is applied, in a repeatable manner, is what
makes it consistently work well or not. I wonder how other professions
have addressed that challenge?
> > Hypothesis: Without a repeatable process, most modelers cannot solve
> > difficult social problems.
> >
> Not true, if one means a step-by-step process that anyone can follow.
> The difficult social problems require a person with a broad and deep
> understanding of the social situation coupled with a successful past
> career of building up through progressively more difficult modeling
> situations.
Problems that were difficult 100 years ago in fields like physics and
chemistry are routinely solved by today's students, as part of their
education. This is not because the problems are described more clearly,
or the students are smarter, or they have successful past related
careers. It's because the tools they use to solve problems are more mature.
Again, you misinterpret what I said. I said ""most modelers."" You are
saying ""anyone."" But then again, we are all speed reading these messages.
But perhaps the hypothesis is weak. Would it be better as: Without a
repeatable process, the field of system dynamics cannot solve difficult
social problems? This is what we're really trying to accomplish. Thanks
for helping me to see this.
> > Corollary: Without a repeatable process, most difficult problem models
> > will be low quality.
>
>Without a solid foundation in underlying fundamentals and an extensive
>background in apprenticeships and practice, ""most difficult problem
>models will be low quality.""
Now we're getting somewhere. There is a large difference between a
repeatable process and ""a solid foundation in underlying fundamentals
and an extensive background in apprenticeships and practice."" The first
is repeatable by average people. The second is not, because users of a
solid foundation can apply that knowledge any way they want. Each
insight requires a large intuitive leap, which varies greatly from
person to person, and depends on brilliance to be right most of the time.
This is a crucial point. Over the 20th century, industry started to see
the importance of formal process. For example, PERT and CPM emerged as
formal processes to manage large projects. The first to use these
techniques was the Manhattan project. People grew tired of too many
large project failures due to project managers merely having a solid
foundation. Something much more was needed. It was a process that fits
the problem. Today, PERT and CPM are required on large US government
projects. For more examples, look at the rise of Six Sigma, Kaizen, and
the countless processes in software engineering.
A formal process takes the best practices found in a solid foundation,
and makes their use less arbitrary and more predictable.
I got the process bug long ago, after reading books like Andrea Gabor's
""The Man Who Invented Quality: How W. Edwards Deming Brought the Quality
Revolution to America."" Page 7 says:
[Deming] advocates a process-obsessed management culture that is
capable of harnessing the know-how and natural initiative of its
employees and fine-tuning the entire organization to higher and higher
standards of excellence and innovation.
What might happen if the field of SD became process-obsessed, in the
sense that Deming met?
>
> Does this not suggest that the process is far simpler than it really
> is? My Urban Dynamics model had two ingredients--my 40 years dealing
> with dynamics in engineering and management, and six weeks of
> discussions, a long half day every week, with a group who had been
> fighting the battle of decaying cities, while I was spending about 30
> hours per week trying to identify a useful model in what they were
> saying.
An insightful point. If you don't have a repeatable process, then you
are forced to rely on the very few people who have 40 years of deep
experience.
A highly productive process can be surprisingly simple. My favorite
example is the Scientific Method, which has these steps:
1. Observe a phenomenon that has no good explanation.
2. Formulate a hypothesis.
3. Design an experiment(s) to test the hypothesis.
4. Perform the experiment(s).
5. Accept, reject, or modify the hypothesis.
> Certainly, the 40 years of background will not be required. Much of
> that experience was without the visible goal of modeling social
> systems. Most of it was dealing with dynamics through the mathematics
> of differential equations rather than the more realistic and easier to
> understand medium of integrations. Most of the time was without the
> clarity of underlying basic principles that are now available and that
> are now teachable. So, we should expect that the 40 years can be
> shrunk to something more like 10 years. At least an intensive year
> should be devoted to truly understanding and appreciating the
> underlying principles of dynamics that are now available.
Thanks for explaining. But how much further could the 10 years of
training in SD be reduced, if we added a process to the foundation?
Plus, currently even 10 years of training is not enough. If it was, then
the field would be solving the great social problems of our time, and it
would be gaining in popularity in the business world much faster.
> Such an attack would allow the process to be iteratively improved
> until the experimental results were stunning, and the hypothesis was
> proven to satisfaction. The output would be (1) a formal process, a
> best practice that we could spread, and (2) a series of cases that can
> be used to teach/test this best practice.
>
> Democracy succeeds because it relies on the rule of law, not men. SD
> too can succeed if it comes to rely on the use of process, not men.
>
> But law needs courts to interpret laws and processes to enforce them.
> In addition to truly understanding the available underlying
> principles, there are processes that are not receiving much
> discussion. The following were offered in my conference talk on the
> next 50 years:
It's good to hear you use the P word at last.
> > "" How often do you see a paper that shows all of the following
> > characteristics?
> >
> > 1. The paper starts with a clear description of the system shortcoming
> > to be improved.
> > 2. It displays a compact model that shows how the difficulty is being
> > caused.
> > 3. It is based on a model that is completely endogenous with no
> > external time series to drive it.
> > 4. It argues for the model being generic and descriptive of other
> > members of a class of systems to which the system at hand belongs.
> > 5. It shows how the model behavior fits other members of the class as
> > policies followed by those other members are tested.
> > 6. It arrives at recommended policies that the author is willing to
> > defend.
> > 7. It discusses how the recommended policies differ from past practice.
> > 8. It examines why the proposed policies will be resisted.
> > 9. It recognizes how to overcome antagonism and resistance to the
> > proposed policies.""
> > Granted, my own models and publications do not meet all of these
> > tests.
Wonderful. In fact, valuable! It's a mother lode of rules worth
following. This is similar to Richard's ""provisional minimal list"" of
model requirements. Standards like these are the first steps toward
establishing a repeatable process. Martin even begins to take those
first few steps, when he writes:
""I find your ""minimal list"" interesting. If such a list of
""deliverables"" could exist, it would help students and in some courses
we might use kind of a form that guides them through the phases.""
And he didn't even use the P word!
Gratefully and warmly yours,
Jack
Posted by ""Jack Harich"" <
register@thwink.org>
posting date Sat, 16 Feb 2008 07:54:21 -0400 (EDT)
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