Why your work is important.

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Why your work is important. The critique of
models and why sensitivity analysis comes in
models under enemy fire?
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The critique of models (see book)
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Todays critique of models
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Michael Crichton presents adversarial opinion
on retreating glaciers and thickness of Antarctic
ice cap sea levels are not rising, he contends.
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They talk as if simulation were real-world data.
They re not. That s a problem that has to be
fixed. I favor a stamp WARNING COMPUTER
SIMULATION MAY BE ERRONEOUS and UNVERIFIABLE.
Like on cigarettes , p. 556
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For sure modelling is subject toady to an
unprecedented critique, which is no longer
limited to post-modern philosophers but involves
intellectuals and scientists of different
political hues. Have models fallen out of grace
and is modelling -- just useless arithmetic as
claimed by Pilkey and Pilkey-Jarvis 2007?
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Useless Arithmetic Why Environmental Scientists
Can't Predict the Future by Orrin H. Pilkey and
Linda Pilkey-Jarvis Quantitative mathematical
models used by policy makes and government
administrators to form environmental policies are
seriously flawed
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One of the examples discussed concerns the Yucca
Mountain repository for radioactive waste
disposal, where a very large model called TSPA
(for total system performance assessment) is used
to guarantee the safe containment of the waste.
TSPA is Composed of 286 sub-models.
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TSPA (like any other model) relies on assumptions
-- a crucial one being the low permeability of
the geological formation and hence the long time
needed for the water to percolate from the desert
surface to the level of the underground disposal.
The confidence of the stakeholders in TSPA was
not helped when evidence was produced which could
lead to an upward revision of 4 orders of
magnitude of this parameter.
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We just cant predict, concludes N. N. Taleb, and
we are victims of the ludic fallacy, of delusion
of uncertainty, and so on. Modelling is just
another attempt to Platonify reality
Nassim Nichola Taleb, The Black Swan, Penguin,
London 2007
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Many will disagree with the works just cited. Yet
our point is the cat is out of the bag already.
Stakeholders and media alike will tend to expect
or suspect instrumental use of computation
models, amplification or dampening of uncertainty
as a function of convenience and so on.
Note for the students The book has a good state
of the art on the sea level rise story.
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The critique of models lt-gt Uncertainty
Peter Kennedy, A Guide to Econometrics
Anticipating criticism by applying sensitivity
analysis. This is one of the ten commandments of
applied econometrics according to Peter Kennedy
Thou shall confess in the presence of
sensitivity. Corollary Thou shall anticipate
criticism
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The spectre of type III errors Assessing the
wrong problem by incorrectly accepting the false
meta-hypothesis that there is no difference
between the boundaries of a problem, as defined
by the analyst, and the actual boundaries of the
problem (Dunn, 1997). answering the wrong
question framing issue (Peter Kennedys 2nd
commandment of applied econometrics Thou shall
answer the right question, Kennedy 2007) Dunn,
W. N. 1997, Cognitive Impairment and Social
Problem Solving Some Tests for Type III Errors
in Policy Analysis, Graduate School of Public and
International Affairs, University of Pittsburgh,
Pittsburgh.
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In sensitivity analysis Type I error assessing
as important a non important factor Type II
assessing as non important an important factor
Type III analysing the wrong problem
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• Type III in sensitivity Example
• In the case of TSPA (Yucca mountain) a range of
  0.02 to 1 millimetre per year was used for
  percolation of flux rate. Applying sensitivity
  analysis to TSPA could or could not identify this
  as a crucial factor, but this would be of scarce
  use if the value of the percolation flux were
  later found to be of the order of 3,000
  millimetres per year.