In article <[EMAIL PROTECTED]>,
dennis roberts <[EMAIL PROTECTED]> wrote:
>>There is a conflict between practice and experience in that a goal of
>>practice is to reach the point where you carry out the procedure
>>WITHOUT THINKING ABOUT THE UNDERLYING CONCEPTS OR PRINCIPLES. It
>>beomes automated and brainless, a skill of the fingers (or toes). For
>>that reason, I think practice should be dispensed only with a doctor's
>>prescription, AFTER one has shown mastery of the concepts. In
>>pracitce our education system tends to work the other way around --
>>try to get everybody to go through the motions and hope a few will see
>>the reasons.
>i would point out however that the notion that we apply principles or
>concepts without thinking is precisely what we really want ... for example,
>a student comes in with some statistical question ... or idea about a
>research project ... and, WITHOUT sitting there 'thinking', you as the
>expert have ready made questions ... suggestions ... paths or leads for the
>student to follow ... THIS is what we do BECAUSE we have practiced these
>'ideas' over and over again. we don't 'think' when we now apply what we
>have learned ...
It is OK to have questions ready, but watch out for the
rest. I am scared about engineering students knowing how
to solve certain types of differential equations, because
they will tend to formulate their problems using only those
differential equations. We have a similar situation with
students using linear regression where it is inappropriate,
or the even worse transforming to normality. Whatever
relationships are present, they are likely to be destroyed
by such methods. I append my five commandments, with some
comments, at the end of this posting.
>think about grading papers ... while students struggle with DOING the paper
>or project .. the GOOD faculty member has no such problem examining and
>finding flaws and good points ... it comes automatically BECAUSE we have
>done it a 1000 times ... this is not bad ... it is good. for, if we did not
>have that 'developed' level of skill ... we would take FORever to grade
>papers ... we would have to RElearn on the spot ... each and every aspect
>of what we are expecting from paper and project work ...
As long as the student is ONLY doing those things which we have
seen on papers, or which we have reasoned students will do, this
is fine. But if it looks different, make sure it is wrong before
marking it wrong, even if you have done it thousands of times
before. What has been learned can be used.
For the client:
1. Thou shalt know that thou must make assumptions.
2. Thou shalt not believe thy assumptions.
For the consultant:
3. Thou shalt not make thy client's assumptions for him.
4. Thou shalt inform thy client of the consequences
of his assumptions.
For the person who is both (e. g., a biostatistician or psychometrician):
5. Thou shalt keep thy roles distinct, lest thou violate
some of the other commandments.
The consultant is obligated to point out how their assumptions affect
their views of their domain; this is in the 4-th commandment. But the
consultant should be very careful in the assumption-making process not
to intrude beyond possibly pointing out that certain assumptions make
large differences, while others do not. A good example here is regression
analysis, where often normality has little effect, but the linearity of
the model is of great importance. Thus, it is very important for the
client to have to justify transformations.
There are, unfortunately, many fields in which much of the activity
consists of using statistical procedures without regard for any assumptions.
--
This address is for information only. I do not claim that these views
are those of the Statistics Department or of Purdue University.
Herman Rubin, Dept. of Statistics, Purdue Univ., West Lafayette IN47907-1399
[EMAIL PROTECTED] Phone: (765)494-6054 FAX: (765)494-0558
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