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From: robison@eosp1.UUCP (Tobias D. Robison)
Newsgroups: net.ai
Subject: Re: Diagnosing strategies for humans?
Message-ID: <1180@eosp1.UUCP>
Date: Tue, 16-Oct-84 18:20:09 EDT
Article-I.D.: eosp1.1180
Posted: Tue Oct 16 18:20:09 1984
Date-Received: Wed, 17-Oct-84 06:35:03 EDT
References: <1339@pucc-h>
Reply-To: robison@eosp1.UUCP (Tobias D. Robison)
Organization: Exxon Office Systems, Princeton
Lines: 55

I cannot suggest references, as requested, but would like to
comment on the interesting fact that most doctors use strategies
of deduction that are not followed in most sciences, businesses,
or professions.  [I'm not a doctor, just a consumer of medical
services.  If anyone feels I have misrepresneted an honorable
profession, please feel free to comment...]

Most doctors tend to diagnose as follows:

They will consider some, but usually not all of the symptoms and
other diagnostic data that are available to them.  They will then
deduce the most common diagnosis that fits most of the information
considered.  ("Common" is used in the sense of "occurring most often".)

If this diagnosis fails as a working hypothesis, the process will be
repeated.  Usually at this point more diagnostic data is available,
or is collected.  Once again, the most common diagnosis to fit the
data considered is obtained (usually excluding the diagnosis
that was rejected).

There is an important exception to this procedure, in that priority
will be given to testing for some well-known possibilities that
require speedy treatment.

Interesting points about this procedure:

- trying to decide what is relevant diagnostic data is itself an
iterative procedure.  I think there is no recognized minimum set of
indications that EVERY doctor will use;  I've seen diagnoses made on
the basis of hardly any data at all.  A practical consideration here
is cost.  Any reasponable comprehenive set of data would be too
expensive to diagnose a common cold.

- diagnoses need not fit all of the available data.  Many symptoms
reported by people are subjective, and many medical conditions can
be present with a great variety of symptoms.  Most people who do
professional deducing would be more likely than doctors to rule a
possibility out or in on the basis of a clear, incompatible symptom.

- This reasoning procedure has a high success rate because:
	+ it detects the most common disorders routinely.
	+ most medical conditions can still be treated even
	  if they are only detected after several mis-diagnoses.

This reasoning process is quite unsettling to anyone who is used to
doing decuctive reasoning in his or her work, and who also has an
unusual medical problem.  Such people will wait impatiently for their
doctors to collect a comprehensive set of data and then select the
matching condition, while the doctors are actually testing a
sequence of progressively less likely hypotheses.

	- Toby Robison (not Robinson!)
	allegra!eosp1!robison
	or: decvax!ittvax!eosp1!robison
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