[Pease Porridge]
Bob's Mailbox
Bob Pease
ED Online ID #20794
March 26, 2009
Copyright © 2006 Penton Media, Inc., All rights reserved. Printing of this document is for personal use only.
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DEAR MR. PEASE,
The “Financial Floobydust” section
of your latest piece is, I think, anything
but floobydust (Jan. 15; ED Online
20410). I believe you have touched upon
a fundamental weakness at the core of so
much financial and macroeconomic modeling,
black-box investing, and other quantitative
aspects of high finance.
As you know, financial practitioners use
models of all stripes to express expectations
for future trends, from the price of
cocoa beans to interest-rate levels. Clearly,
the industry’s track record with respect
to modeling such expectations has been
abysmal for the last decade. And we do not
appear to be getting any better at it.
I believe that financial practitioners must
reassess some of our most basic forecasting
practices, from the assumptions that go
into our models to the techniques we have
for generating output. I especially think
that practitioners are too trigonometryimpaired
(having not once, that I can recall,
seen a wave function to forecast cyclicality
or to project a detrended data series in the
10 years that I have worked as an analyst in
capital markets).
In short, I think financial analysts have
a lot more to learn from electrical engineers—
with their practical, hands-on
modeling skills—than from the theoretical
physicists and pure “quants” behind every
discredited financial model from long-term
capital management to the CDS securitizations.
The industry is looking in the wrong
place, for the wrong kind of math—and
finding it, to the repeated detriment of the
global economic system.
I am nearing completion of a book entitled
Fringe Statistics: The Hunt for Crisis-
Proof Financial Models. The goal is to
describe, in a way that financial practitioners
can understand, how best to “import”
certain time-tested, disciplined quantitative
techniques broadly used in other fields to
the field of finance (as well as to resuscitate
certain techniques once at use in my field,
but which have fallen by the wayside).
Unfortunately, I don’t know any electrical
engineers with whom I could “kick the
tires” on this subject. And I believe it is
critical that I get input from true scientists.
I respect your viewpoint and would very
much appreciate the opportunity to speak
with you by phone. (Informally and “off
the record” is fine. I am not a journalist,
just a budding author.)
TROY PEERY
HELLO, TROY PEERY,
Yeah, we agree on many things. Let’s
talk. I’ll give you a call one of these mornings.
But I would be very cautious about
your phrase “Crisis-Proof Financial Models.”
I would tend to say “Crisis-Resistant...”
On the other hand, the models we
have seen recently were pretty disastrous,
weren’t they? Best wishes.
RAP
HI MR. PEASE,
I work with piezoelectrics, so the topic
of boost converters is always of interest,
particularly getting 3 to 12 V dc (That 4:1
range is brutal! If we could do it from 6 to
12 V, would that be okay? /rap) up to 150 V
dc or so, at up to 10-W power levels. (Yeah,
all you want is 70 mA out for 4 A input.
/rap) With high efficiency. In zero space. I
seem to be hampered by two things.
First, published suggestions for operating
conditions, and standard formulas
that work fine for most LV converters,
yield poor efficiency and/or smoke when
applied to HV boost converters. Ringing
between inductor and diode can be excessive,
and my low-RDS HV MOSFETs have
huge gate capacitances that prevent me
from working at the frequencies necessary
to use reasonably sized components. I’m
not even sure my inductors are good at
the frequencies where I want to use them.
My customer has a saying, “fight for every
millimeter,” and displays more than a little
terror when confronted with an inductor
that’s larger than an 0805 resistor.
(I may be able to sell you a “Camel
Amplifier.” That is a circuit, no one part
of which is so hard, but the total system
becomes impossible. /rap)
Second, we want off-the-shelf parts, and
there never seems to be enough information
about commercial inductors to calculate
a design. It always ends up being
trial and error in the form of “Install a
smaller part. If it burns up, go one size
larger.” Shades of Muntz TV. So, do you
have any advice for designing HV converters?
Ideally, a list of pitfalls unique
to HV boost circuits and how to address
them. Is an 85% to 95% efficiency converter
even possible in the boost configuration?
CONRAD HOFFMAN
HELLO CONRAD,
With all your conditions? Probably not.
That is beastly hard. I’ll ask around. You
want it to be SC-proof on the output, too?
My move.
RAP
PEASE TO AMARILLO
I got a letter from a guy named Michael
asking for help on a high-Z problem. But
he didn’t include his address, his e-mail
address, his phone or fax number, or even
his last name. If the postal service hadn’t
stamped “Amarillo” as the postmark, I
wouldn’t even know how to identify him
at all. So, Michael, you’ll have to give me
more info before I can help you.
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