At 04:42 PM 4/19/01 +0000, Radford Neal wrote:
>In article <[EMAIL PROTECTED]>,
>dennis roberts <[EMAIL PROTECTED]> wrote:
>
>I don't find this persuasive.
nor the reverse ... since we have NO data on any of this ... only our own
notions of how it MIGHT play itself out inside the heads of students
> I think that any student who has the
>abstract reasoning ability needed to understand the concepts involved
>will not have any difficult accepting a statement that "this situation
>doesn't come up often in practice, but we'll start with it because
>it's simpler".
this in and of itself sounds strange ... "this situation doesn't come up
often in practice ... but we will being with it ... (forget the reason why)
... "
when does it EVER come up in practice, really? i know there must be some
good examples out there for when it does but ... i have yet to see one ...
where one would KNOW the sd but not the mean too ...
for sure, it would not be based on data the investigator gathered ...
since, to get the sd you would have to have the mean ... so, it must be
(once again) one of those where you say "assume the sd in the population is
... " ... and hope the students buy that ...
>I have my doubts that introducing the t distribution is "NOT hard", if
>by that you mean that it's not hard to get them to understand what's
>actually happening. Of course, it's not very hard to get them to
>understand how to plug the numbers into the formula.
just as i have doubts that the converse ... that introducing the z approach
is easy ... as far as i can tell (again, no data ... just conjecture) the
only thing that could make it easier is that (if one sticks to 95% CIs or
.05 as a p value level criterion for a hypothesis test) ... you only have
to remember 1.96 ...
can someone elaborate on why fundamentally, using z would be easier OTHER
than only 1 CV to remember? i don't see how it makes the basic notions of
what CIs are and what you do to conduct hypothesis tests ... easier in some
ideational or cognitive way
what would the train of cognitive thought BE in the z approach that would
make this easier?
>I think one could argue that introducing the z test first is MORE
>realistic.
this seems inconsistent with your earlier suggestion that " ... this does
not come up in practice very often ... "
After seeing the z test, students will
>realize how lucky one is to have such a statistic,
hmmmm ... this is a real stretch
for most students, being "lucky" is finding out that he/she does NOT have
to take a stat course and therefore can avoid all this mess!
none of this applies to really good students ... you can introduce almost
any notion to them and they will catch on to it AND quickly ... the problem
is with the general batch which is usually 90% or more of all these
students you have ... especially in first level intro stat courses ...
> Radford Neal
>
>
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_________________________________________________________
dennis roberts, educational psychology, penn state university
208 cedar, AC 8148632401, mailto:[EMAIL PROTECTED]
http://roberts.ed.psu.edu/users/droberts/drober~1.htm
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