[comp.ai] Data Interpretation - Diagnosis expert Task

jberger@asterix.drev.dnd.ca (Jean Berger) (11/07/90)

	Would someone help me in clarifying in an unambiguous manner
	the real difference between two kind of expert tasks namely:

	- Data Interpretation and
	- Diagnosis

	By unambiguous manner I mean an easy way to PARTITION tasks domain
	concerning respectively Diagnosis and Data Interpretation in a unique
	manner. Sometimes it might be hard to distinguish Data Interpretation
	from Diagnosis tasks, what are the basic fundamental elements
	discriminating each other.

	Hope that may help some people to discriminate clearly between the 
	two expert tasks.

	Thank you.


 -- Great Minds Think Alike
========================================================================
jean berger Eng.                       Defence Research Establishment
                                       Command and Control Division
                                       Combat System Section
                                       C.P. 8800 Courcelette, Quebec
                                       Canada
                                       G0A - 1R0
PHONE: (418) 844-4645
FAX:   (418) 844-4538

E-MAIL: ARPA:  jeanb@quebec.drev.dnd.ca
=========================================================================

byland@iris.cis.ohio-state.edu (Tom Bylander) (11/09/90)

In article <1990Nov6.184658.29097@asterix.drev.dnd.ca> jberger@asterix.drev.dnd.ca (Jean Berger) writes:
>
>	Would someone help me in clarifying in an unambiguous manner
>	the real difference between two kind of expert tasks namely:
>
>	- Data Interpretation and
>	- Diagnosis

I would say that diagnosis is a subclass of data interpretation, i.e.,
a fault hypothesis is an interpretation of the observations.
Diagnostic reasoning, however, is often associated with data gathering
and test generation, both of which are probably considered separate
from data interpretation.

Data interpretation is also closely related to abduction, which is
finding explanations for data.  Perhaps it would be best to consider
explanations as a subclass of interpretations, making abduction a
subclass of data interpretation.

So I would roughly put the relationship this way.  Abduction is data
interpretation in which the interpretation is an explanation of the
data.  Diagnosis is abduction where the data are abnormal observations
and the explanation is a (composite) fault hypothesis.
							
Tom Bylander
byland@cis.ohio-state.edu

sticklen@cps.msu.edu (Jon Sticklen) (11/10/90)

From article <85816@tut.cis.ohio-state.edu>, by byland@iris.cis.ohio-state.edu (Tom Bylander):
> In article <1990Nov6.184658.29097@asterix.drev.dnd.ca> jberger@asterix.drev.dnd.ca (Jean Berger) writes:
>>
>>	Would someone help me in clarifying in an unambiguous manner
>>	the real difference between two kind of expert tasks namely:
>>
>>	- Data Interpretation and
>>	- Diagnosis
> 


I think that Tom Bylander captured most of what I would say to this
question too. But I would add one other discriminant between "data
interpretation" and "diagnosis." 

Diagnosis should not be considered as an isolated task. The bottom
line when we do diagnostic problem solving is not that we want to
find out "what is wrong" but rather that we want to "fix what is wrong."
Diagnosis is problem solving aimed at characterizing what is wrong, but
the output of diagnositic problem solving is then used to fix what is 
wrong. If we are doing classification-based diagnosis, then the diagnositic
categories for any real world problem will surely have therapy utility.
In fact, that is what diagnostic categories are - equivalence classes
which map situations into appropriate therapies.

So at root I agree with Bylander that diagnosis is a subset of data
interpretation. What I am adding is why its a subset. And that why is
that the output of diagnostic problem solving must have utility for
fixing something that is broken.

	---jon---


Jon Sticklen
AI/KBS Lab - CPS Dept
Michigan State University

mtanner@gmuvax2.gmu.edu (Michael C. Tanner) (11/13/90)

This is mostly a response to <byland@cis.ohio-state.edu> and
<sticklen@cpswh.cps.msu.edu>.

I wish somebody would define data interpretation.

You normally have to interpret data in order to do diagnosis.  You may choose
to view the result of diagnosis as an interpretation of data.  But unless
there's some technical definition of data interpretation that I'm missing, I
don't think one is a subset of the other.

Both are really ways of "finding out what's true".  I don't think that's the
same as "inference to the best explanation" (IBE) (similar to abduction).  If
you have the prior assumption that there's something wrong, you might attempt
to find out what's true (i.e., what's wrong) by diagnosis, which you may
choose to view as a problem of inferring the best explanation.

So I disagree with Bylander when he says diagnosis is a kind of data
interpretation and data interpretation is abduction.  But I agree with
Sticklen (and I think Bylander too) that diagnosis carries the explicit
assumption that something is wrong and the diagnostic answer will say what's
wrong.

IBE, and data interpretation, and (especially) finding out what's true, are
too ill-specified to be of any direct use.  All problem solving is done with
some purpose, and that purpose introduces some pragmatic considerations.  I
don't think you can just interpret data.  You have to interpret it with some
use in mind for the result.  Diagnosis is a possible use, i.e., you might
interpret data in order to use it for diagnosis.  Diagnosis intoduces the
consideration that something is wrong and acceptable answers will specify
faults and perhaps explain how the faults produce the misbehavior that made
you aware of the problem.  And as Sticklen points out, the goal of treatment
or repair (a subgoal of which might be diagnosis) introduces the consideration
that the diagnostic answers will relate to possible treatments.

So my answer (modulo the real meaning of data interpretation) is:  diagnosis
is a kind of problem solving and data interpretation isn't.


--
Michael C. Tanner                         Assistant Professor
CS Dept                                   AI Center
George Mason Univ.                        Email: tanner@aic.gmu.edu
Fairfax, VA 22030                         Phone: (703) 764-6487