[From Bill Powers (940724.1730 MDT)]
Bob Clark (940724.1408 EDT) --
Just consider this system diagram:
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x ---> || INTEGRAL A*2X/DT^2 + B*DX/DT +CX || --> y
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To me, this expression expresses the "dynamic characteristics" of a
system with parameters "A," "B," and "C." As the general form of a
linear, second order differential equation, it is familiar, and has
the "solutions" that you present as "flow-chart versions."
To me, this "box" is not a "system diagram." To be such a diagram, at
least two boxes are required.
In my book, too. I meant only to illustrate what one box in a system
diagram would look like. The rest of the boxes would be defined
similarly. That seems to be something of a side-issue.
Dictionary:
"system, n. 1. an assemblage or combination of things or parts
"forming a complex or unitary whole. etc."
Thus a "system diagram" is composed of a set of "boxes" and
"interconnections among boxes." The "contents" of the boxes and
locations of the interconnections determine the overall dynamics of
the assembly.
This definition is inadequate for systems analysis. A tower made of
assorted children's blocks, or a painting, would satisfy it. It seems to
be based on superficial appearance rather than function.
Such a diagram can apply to, but need not be limited to, closed loop
situations.
Yes. It can apply to almost anything that's not merely a random jumble.
System diagrams, as they are used in B:CP and network discussions,
are consistent with this definition.
That is mainly because the definition is so broad as to be useless. It
classes together things like control systems, S-R systems, houses,
symphonies, and mountains.
Such a diagrams can also be interpreted as representing a temporal
sequence of events within the system.
Not the diagram reproduced above. I think you're missing my point. There
is a superficial visual resemblance between a system diagram and a flow-
chart. Conceptually, however, they are totally different. In a system
diagram, for example, there is no implication of temporal sequence in
the arrows connecting blocks. All the blocks are assumed to be in effect
all of the time.
I overlooked the difference between your phrase, "how a system
behaves," and the dictionary definition:
"flow chart, 1. also called FLOW SHEET, a detailed diagram or chart
"of the operations and equipment through which material passes, as in
"a manufacturing process. _Computer Technol._ a graphic
"representation, more detailed than a flow diagram, of a sequence of
"operations in a computer program."
and:
"flow diagram, _Computer Technol._ a schematic representation, less
"detailed than a flow chart, of a sequence of subroutines, indicating
"the general flow of information for solving a problem by a computer."Both of the definitions, of "flow chart" and of "flow diagram,"
emphasize a "sequence" of "operations." This is a "temporal"
sequence: A before B, before C, etc.
I think my definitions of system diagrams and flow charts are preferable
to those from the dictionary that you cite. At least I prefer them. The
distinction between "chart" and "diagram" is completely arbitrary. And
you will note that in both definitions, there is implied a progression
through the diagram, as if one operation takes place at a time. That
aspect of the definition I agree with. In a system diagram, no such
step-by-step progression is implied. In a system diagram, we do not have
A before B before C: we have A, B and C all in effect at the same time.
If the time intervals involved are considered small compared to time
variables of interest, the operation diagrammed can be regarded as
"instantaneous." Thus a flow chart can be regarded as describing the
structure of a system, that is: a "system diagram."
I disagree. A flow chart is about the behavior of variables. A system
diagram is about the forms of functions and their interdependencies.
An open loop system is intended to provide an individual with
improved control of his environment. That is, it is intended to
improve an individual's ability to keep his perceptions of his
environment close to his desired perceptions.
When the individual user is included in the system, such open loop
systems serve as portions of the user's output function. Thus they
support the users own ("negative feedback") control systems. The
user completes the system by providing the feedback function, the
comparator and the reference variable.
Agreed.
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Bill Leach (940724.13:59 EDT) --
I am led to believe that the "MMPI" (Minosota Multiphasic Personality
Inventory) is actually a "decent test" Of course I have that "belief"
without much justification.
Does anyone out there have any actual correlations between MMPI scores
and performance scores on anything?
I have nothing against any test that gives usable results and does not
harm the individual through the uses made of it. I believe in the
usefulness of statistical analysis when appropriately employed. I am not
an anti-statistics ideologue. All I am doing, when I point out flaws in
the uses of statistics, is presenting what I believe to be the facts of
the matter, without introducing any gratuitous opinions as far as I
know. If you believe that misclassifying 20 or 30 or 40 percent of the
people who take a test is acceptable, be my guest. All I ask is that
there be a public acknowledgement of this bare fact. If everybody can
just agree on the actual consequences of using mass measures as the
basis for evaluating individuals, the rest of the debate is in the area
of ethics or morality or politics. Perhaps somebody can make a
convincing case for discounting the importance of the
misclassifications. One such case can be made on the basis of the
principle that the good of the organization must come before the good of
the individual -- you can't make an omelet without breaking eggs. I
don't happen to share that view, but that's a different argument.
...by the way, for what ever it is worth, in that industry questionable
results from the MMPI are the bases for an interview with a
psychiatrist.
Nice. Then when you apply for health insurance, how will you answer
questions like "Have you ever been referred to a mental health
professional on the basis of a diagnosis of mental disorder?" If you
answer "yes", you will be turned down because of a pre-existing
condition. If you answer "no" you will have lied on your application,
having affirmed the truth of a statement you know to be untrue. If that
is discovered, you will lose all possibility of being covered for
anything.
It also makes sense that "industry" would want to have a means of
determining in advance if they are potentially hiring a person with a
strong reference for killing others or a reference for something like
"whatever you can get away with is OK".
Do you think that an intelligent psychopath who believes that whatever
you can get away with is OK or who likes to kill people would hestitate
to lie about his beliefs and preferences on a pyschological test? Such
tests, of course, do not contain questions like "Is it OK to do anything
you want if you're not caught?" or "Do you like to kill people?" That
would obviously invite lying. Psychopaths are not stupid. So what is
done instead is to try to ask questions which get at underlying
motivations and tendencies indirectly, by asking about innocent-seeming
things that don't reveal what the tester is trying to discover.
Unfortunately, the indirectness of the questions and their very
innocuousness leaves room for incriminating answers that are actually
quite innocent of base motivations.
Since some psychopaths do sometimes answer certain innocent questions in
a particular way, anyone who answers the same questions in the same way
becomes tainted with "indications" of psychopathic "tendencies." And as
soon as such test scores come back, interviewers begin to perceive the
person who took the test not as just another applicant, but as a
possible psychopathic personality. Now every hestitation or indication
of nervousness takes on a new meaning, supporting the initial impression
created by the test score. Even reluctance to answer certain questions
like "How often did you masturbate when you were in high-school" is put
down not to embarrassment, but to evasiveness; these more "penetrating"
questions don't even get asked unless the test score arouses suspicions.
The interviewer then puts down in the record, "Subject uncooperative."
But the most damning entry is "Referred for psychiatric evaluation."
Look at what has happened in recent political campaigns to candidates
who admitted or were discovered to have undergone psychological
counseling. Instead of the news media treating this as an indication
that the candidate is probably now in better mental condition than most
of the other candidates, they treat it as if the candidate had some sort
of permanent disability: nobody gets psychotherapy if they aren't crazy,
do they?
These are the wheels you set in motion when you misevaluate an
individual by using psychological tests producing scores that are less
than perfectly correlated with whatever they are supposed to indicate.
Whether you continue, knowing these consequences, to evaluate people by
using tests that you know for certain will misclassify a certain
substantial percentage of them depends on your system of values. If your
loyalty is to some entity called "the company" or "the organization,"
then you will place the good of the company above the problems you
create for some minority of individuals. A dispassionate decision is
made more difficult by the fact that almost invariably it is "the
organization" that pays you for administering the test and making the
evaluations. The decision can't be free of self-interest.
What I am trying to do by laying out the facts about the reliability of
test scores and the consequences of misevaluating people is to bring
something to awareness that will create a painful conflict inside most
people in this sort of occupation. I can't tell anyone how to resolve
this conflict; all I can do is point it out. I have, in fact,
considerable confidence that any ordinary person who becomes aware of
this conflict will try quite hard to resolve it much as I would do. But
there's no predicting what reorganization will produce.
So what can PCT say to the personel manager? What direct, ready to
implement, practical improvements does PCT offer this person? I am not
being sarcastic here and am quite serious. This manager has "data"
that shows that what he is doing now improves his chances of success in
the process marginally but enough to make a significant difference "to
the bottom line".
PCT says that you will choose actions that bring your world as close as
possible to matching _all_ the standards you have chosen as desirable.
It says that in the face of serious conflict, you will suffer errors
that will probably lead to reorganization, and that when the
reorganization is successfully completed, you will find your world
closer than before to the state you prefer, at all levels. PCT says that
you will control your own world better, in the long run, if you perceive
it as accurately and consistently as you can.
PCT is not in the business of making people feel better about doing
things they themselves recognize as conflicting with their own
standards.
It is all well and good to tell him how bad his current system is and
he might even agree with you but unless you can offer him something
workable then all he will do is listen (if that).
If the personnel manager recognizes the problem and experiences a
conflict of values because of this recognition, I have done all I can.
How to resolve that conflict is up to the personnell manager: a very
private affair. Some managers will say "If I don't do it, somebody else
will," thus renouncing responsibility for the consequences of their
actions. Some will say "All those people who slip through the cracks
just have to work out their own destinies." Some will quit their jobs,
or campaign against psychological testing until they win or get fired.
Some will say, "It's a tough world and I'm not about to give up this
position because some do-gooder wants me to hire any sort of riff-raff."
As I say, there's no predicting the outcome of reorganization, or even
whether reorganization will start.
That's not a problem I can solve.
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Hank Folson (940724) --
On defining terms:
"On" refers to "concerning" or "having to do with," not a spatial
relationship.
"Defining" means offering sentences which refer to experiences of a
different detailed sort than the terms actually being defined (a
recursive definition).
"terms" refers to arbitrary words, not to lengths of time in office or
in jail.
"Refers to" means "being used to refer to"; that is, to point in some
way or indicate, or call to attention, or choose as a subject matter.
"concerning" means -- uh -- referring to, or having to do with.. Uh...
"not" means negation, applied to whatever statement follows.
"spatial" means having to do with space, or linear dimensions.
"relationship" means -- uh -- relationship.
"having to do with" means "in some way concerned with" or "in some way
referring to" or
"arbitrary" means chosen for no definable reason.
"reason" means ....
"means" means ..
I give up.
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Best to all,
Bill P.