00100		CHAPTER 9
00200	
00300			   MODEL EVALUATION
00400	
00500		Evaluation procedures  for  models  involve  the  disarmingly
00600	simple question - `how good is the model?' The ordinary language term
00700	`good' in general means praiseworthy. But what is a model  `good  as'
00800	or `good for' in order to be praiseworthy? A model can be deemed good
00900	as a representation or good for an application. Our  primary  aim  in
01000	constructing  this  model  was  to  explore  and test a theory having
01100	explanatory verisimilitude. To satisfy this aim the model  must  meet
01200	norms  of  internal  consistency and norms of external correspondence
01300	with observed phenomena. A secondary aim involved pragmatic norms  of
01400	application.  These  aims  are  not  unrelated  but the first is more
01500	fundamental  since  useful  applications  require  some   degree   of
01600	consistency and verisimilitude.
01700		A model in the form of an algorithm consists of a structure of
01800	mechanisms whose inner workings are sufficient to generate the outward
01900	behavior under consideration. The theory embodied in the model is
02000	revealed by the set of statements which describes how the structure
02100	reacts under various circumstances.
02200		Theories have many functions. They can be summarized as follows
02300	[from Bunge?]
02400		(1)To systematize knowledge.
02500		(2)To explain facts by showing how they are the entailed
02600	              consequences of the systematizing hypotheses.
02700		(3)To increase knowledge by deriving new facts.
02800		(4)To enhance the testability of hypotheses by connecting them to observations.
02900		(5)To guide research by:
03000	              (a)posing fruitful problems
03100	              (b)suggesting new data to gather
03200	              (c)opening new lines of investigation
03300		(6)To map a portion of reality.
03400		It is a tall order for a theory to fulfill all of these
03500	functions. In undeveloped fields we should be happy with even one  of
03600	them.   Models   can  be  assigned  these  functions  when  they  are
03700	theoretical, rather than replicative, in type. Our model was intended
03800	primarily to serve functions (2) and (4), testable explanation.
03900		What constitutes a satisfactory explanation has been  treated
04000	in  section  00.0.  The  `fit'  or  correspondence  with phenomena as
04100	indicated by measurements and empirical tests indicte truth,or grains
04200	of  truth  showing  promise for turning out to be true. Our tests and
04300	measures were described in section 000.0. Acceptability  of  a  model
04400	sometimes  depends not so much on truthlikehood, an elusive state, as
04500	on whether a majority of the relevant expert community  believes  the
04600	theory  or  model to approximate truth to some unknown and unknowable
04700	degree and be better than their rivals. Truth or  falsity  cannot  be
04800	proven  with certainty but their presence can be assayed by some sort
04900	of critical assesment and deliberation. A theory or model  may  bring
05000	cognitive  or  pragmatic comfort, not because it is TRUTH but because
05100	it represents an improvement  overits  contending  rivals.  Cognitive
05200	comfort  is  a  type  of  intellectual  satisfaction  while pragmatic
05300	comfort accrues from applications to problems in order to make things
05400	work the way humans want them to work in contexts of action.
05500		It would be a bonus if our model could satisfy those interested
05600	in function(3) listed above, making possible new knowledge through prediction.
05700	This novelty could arise in two ways. First the model might demonstrate
05800	a property of the paranoid mode hitherto unobserved clinically.  
05900	In principle this could come about because the I/O behavior of the model
06000	is a consequence of a large number of interacting hypotheses and assumptions
06100	chosen initially chosen to explain frequently observed phenomena. When the
06200	elements of such a complex conjunction interact with input they generate consequences
06300	in addition to those they were designed to explain. Whether any of these
06400	consequences are significant or characteristic of the paranoid mode remains
06500	a subject for future study.
06600		A second source of novelty would lie in the behavior of the model
06700	in some new situation. Since it is designed to simulate communicative
06800	behavior in an interview situation, the `new' circumstance would have to
06900	involve some new type of linguistic interaction which the model is capable
07000	of responding to. From its behavior one might then predict how paranoid
07100	patients would behave under similar circumstances. the requiste
07200	empirical tests and measures would show the degree of correspondence
07300	between patient and model behaviors.
07400		This possibility is of importance in considering therapies for
07500	patients caught in the quandaries of the paranoid mode. Language-based
07600	or semantic techniques do not seem very effective in the psychoses
07700	but they are useful in states of lesser severity. A wide range of
07800	new semantic techniques, including extremes, could be tried first on
07900	the model without hurting patients through blind experimentation.
08000		While we have used the model to explore a theory and to
08100	study psychiatric judgements, its potential use as a training device
08200	has not escaped out attention. Mental health professinals in their
08300	training need `disposable' patients to practice on. A model has the advantage
08400	of not being harmable and providing an opportunity to measure performance.
08500		A theoretical model is evaluated relative to rival explanations.
08600	Our model stands as a contender for the preferred psychological explanation
08700	of paranoid processes. The expert forum will decide its ultimate status.
08800	A theoretical model is partial, perspectival and has a short half-life.
08900	Hopefully it lives long enough to provide a first approximation from
09000	which better approximations can develop.