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Topic: [ap-stat] 2009 FR #2 rubric
Replies: 1   Last Post: May 9, 2011 4:59 PM

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Charles Peltier

Posts: 684
Registered: 12/6/04
Re: [ap-stat] 2009 FR #2 rubric
Posted: May 9, 2011 4:59 PM
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Here's a copy of (most of) an exchange on this topic in 2008, when there
was a reference to acceptability of a calculator term. The long-winded
part is my writing, which met with approval from a number of more
exeprienced people.
The key issue isn't penalizing calculator speech - it's ignoring
(treating as blank) any language that isn't the standard language of

Hope this helps to clarify the situation
Charlie Peltier
Saint Mary's College
Notred Dame, IN

I'm going to amplify this, for those who have not been readers:

Note the qualification here of "if the student identifies what each of
the values input represented".
As a reader, if I see the line

binomial pdf (10, .17 , 2) = .2929

that Jeff posted, I am looking at a language that is not the standard
language of statistics. [Same problem if I see "PDF 2; binomial 10 .17."
- which is in a language more common to statistical work but which is
still not the standard language]..The reader is not expected to
memorize and translate foreign languages (and especially without Catalog
Help) - not Latin, not Minitab or SPSS or SAS (all more common than TI)
grammar. The student who writes *only* this has failed the
"communication" part of the task of comuicating the statistical work
done. The fact that "Catalog /Help" is very popular makes it clear that
many of the people who would write this don't remember what it means, either

If, as reader, I see "binomial pdf (10, .17, 2) n=10, p=.17, x=2" then I
have been given enough information to ignore the weird grammar and
*read* "binomial, n=10,p=.17,x=2" [I also see "pdf" which is a standard
notation and distinguishes from the cumulative distribution -but I'm
probably not worrying about that unless the distinction is critical in
the context of this problem] - which is all I need to know.

Even if the "n=10, etc." doesn't appear on the same line of writing, or
is given in words, - if the information is there, I'm good. The key is
that *all* the calculator command tells me is that I have "binomial" and
"density" and "these numbers go with it, somehow". Some standard
notational (maybe very telegraphic - but stnadard notation] indication
of the meanings is still needed.

It's not true, as some people have said, that "Calculator notation is
penalized". It is true that readers are not expected to read it, except
for obvious pieces like "normal" or "binomial". If other text fills in
the relationships of the numbers written in some cryptic order, then
that fills the gap.
Hope this helps - it's based on my experience as a reader.

Charlie Peltier
Saint Mary's College
Notre Dame, IN

Nancy Dorff-Pennea wrote:

> I recall that at the reading last year we were told that a calculator command for a normal probability was accepted as "work" provided that the student identified what each of the values were input represented. When I went over the binomial probaility question on the practice exam with my students this is what I told them. I'm interested to know if there is general agreement with this or not?
> Nancy Dorff-Pennea
> Suncoast HS
> Riviera Beach, FL
> ____________________________
> From: Jeff Parker []
> Sent: Wed 4/30/2008 8:35
> ....
> Does that mean that this is an acceptable answer:
> binomial pdf (10, .17 , 2) = .2929?
> ...Not clear to me what constitutes "work" in this context.

Larry Ottman wrote:
> Apologies if this has gone around before, I did a "little" searching of the archive and didn't see anything. So after months (and years) of telling my students NEVER to write a normcdf or invnorm on a piece of paper, I stumbled on the rubric for this question that seems to encourage it's use.
> I understand the need for the three pieces (distribution, parameters, calculation). My reading of the rubric seems to imply that a sketch with a calculated answer would only be an E IF it included the actual calculator command. I have always told my students to draw and label the sketch and just say "by calculator". Anyone who was around for this care to clarify or correct my understanding?
> Thank you
> Larry
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