Donald Burrill wrote:
>If the data are normally distributed (or even approximately so, what
>seems to be called "empirically distributed" these days), the 3rd
>quartile + 1.5 IQR locates a point 2.0 std. devs. above the mean;
>symmetrically, the 1st quartile minus 1.5 IQR gets you 2.0 SDs belo
all of this is assuming of course, that some extreme value ... by ANY
definition ... is "bad" in some way ... that is, worthy of special
attention for fear that it got there by some nefarious method
i am not sure the flagging of extreme values has any particular value ...
certainly, to flag an
I wrote:
> Er, no.
>
> Q1 ~ mu - 2/3 sigma
> Q3 ~ mu + 2/3 sigma
> 1 IQR ~ 4/3 sigma
> 1.5 IQR ~ 2 sigma
>
> inner fence ~ mu +- 2 2/3 sigma which is about the 0.5 percentile.
-right so far -
and then burbled
> The inner fences are s
Donald Burrill wrote:
>
> On Tue, 28 Aug 2001, Dennis Roberts wrote in part:
>
> > however ... the "flagging" of "outliers" is totally arbitrary ... i
> > see no rationale for saying that if a data point is 1.5 IQRs away from
> > some point ... that there is something significant about that
>
On Tue, 28 Aug 2001, Dennis Roberts wrote in part:
> however ... the "flagging" of "outliers" is totally arbitrary ... i
> see no rationale for saying that if a data point is 1.5 IQRs away from
> some point ... that there is something significant about that
If the data are normally distributed
Eric Bohlman wrote:
> Robert J. MacG. Dawson <[EMAIL PROTECTED]> wrote:
> > If indeed the scores are being reduced by hiding the easy questions
> > among the harder ones, then I would say yes, this is a defect of the
> > current system, and should be changed. It may be that the questions
>
At 11:30 PM 8/28/01 +, Jim Callahan wrote:
>Eric Bohlman wrote:
>
> >And furthermore, not all the wrong answers are equally "bad." Someone who
> >would answer A or B must know quite a bit less than someone who would
> >answer C (in fact, it would tend to indicate that they had no concept at
>
At 10:43 PM 8/28/01 +, EugeneGall wrote:
>I got an email from Anand Vaishnav, the Globe reporter who did Friday's
>article
>on the math and stats problems in MCAS. Only about 50% of the 63000 10th
>graders in MA got median and range. I suspect that mean and range
>probably was
>the most po
Eric Bohlman wrote:
>And furthermore, not all the wrong answers are equally "bad." Someone who
>would answer A or B must know quite a bit less than someone who would
>answer C (in fact, it would tend to indicate that they had no concept at
>all of what the boxplot represented).
I don't belie
Dennis Roberts <[EMAIL PROTECTED]> wrote:
> if we take the infamous #39 item ... where the options were (if i recall)...
> A. mean only
> B. median only
> C. range and mean
> D. range and median
> well, even if we accepted this item as "fair" ...
> a student looks at the graph ... sees that th
I got an email from Anand Vaishnav, the Globe reporter who did Friday's article
on the math and stats problems in MCAS. Only about 50% of the 63000 10th
graders in MA got median and range. I suspect that mean and range probably was
the most popular incorrect answer (according to the MCAS graders
Robert J. MacG. Dawson <[EMAIL PROTECTED]> wrote:
> If indeed the scores are being reduced by hiding the easy questions
> among the harder ones, then I would say yes, this is a defect of the
> current system, and should be changed. It may be that the questions
> themselves ought to be more d
At 01:33 PM 8/28/01 -0500, Jay Warner wrote:
>Suggest we step back a minute.
by de facto definition ... the MCAS tests ... are intended to convey ...
MINIMUM skills/knowledge that they expect all high school GRADUATES to have
... they certainly cannot purport to test and/or represent anything h
Suggest we step back a minute. What do we want the test to measure?
Could be recognition level knowledge, could be recall level, could be a
higher level. (these two are easy to do with multiple guess questions,
so they get used a lot.) A student who is experienced or adept at
dealing with mul
At 02:21 PM 8/28/01 +, NoSpam54 wrote:
> If there were an AP stats course, they would probably be using a
>college-level text that would be using a true Tukey boxplot, not the
>Harcourt-Brace/NCTS boxplot. I don't think it fair for students to know that
>the NCTS and the K-12 textbook writ
Dennis Roberts wrote:
At 01:57 PM 8/27/01 -0300, Robert J. MacG. Dawson
wrote:
[snip] yeah but ... they could do that from day 1 ... in a CAT
format ... the
first time 10th graders take the test ... why wait till retake 3 or
retake 4?
why waste 10th graders time the first go round ...
A p
NCTS should be NCTM in my previous post
The NCTM web page, with links to their boxplot (different from the Tukey
boxplot) is at:
http://www.nctm.org/
For some reason, the NCTM boxplot extends the whisker to cover all data outside
the box, thus completely gutting the major role of the Tukey boxplo
Chris Olsen wrote:
>(1) I would think it highly unlikely that even your poor school districts
>are using textbooks from the circa 1976-1980 period. If (in the incredibly
>unlikely event that a textbook would actually last 20 years) any of your
>schools have such dinosaurs, the occurence of a Tu
At 11:13 AM 8/28/01 -0300, Robert J. MacG. Dawson wrote:
> If indeed the scores are being reduced by hiding the easy questions
>among the harder ones, then I would say yes, this is a defect of the
>current system, and should be changed. It may be that the questions
>themselves ought to b
Dennis Roberts wrote:
> of course, research eons ago has shown that test performance is optimized
> ... by having items in the order of easy to difficult ... IF there is a
> time limit where some examinees have to push to get finished
>
> now that's a thought ... maybe if the items WERE ordere
At 09:23 AM 8/28/01 -0300, Robert J. MacG. Dawson wrote:
>I wrote:
> >
>
> > > An obvious approach that would seem to give the advantages hoped for
> > >from the focussed test without the disadvantages would be just to group
> > >questions in the original test in roughly increasing order of
> > >
I wrote:
>
> > An obvious approach that would seem to give the advantages hoped for
> >from the focussed test without the disadvantages would be just to group
> >questions in the original test in roughly increasing order of
> >difficulty.
which, I think, answers Dennis' question.
"Robert J. MacG. Dawson" wrote:
> The focused test eliminates questions that would
enable students to score A's,
> B's, and C's. All they get is another chance to score a D rather
than an F.
> Implicit in the very concept of the focused test is the idea that
a student who
> fails the standard MC
I just took another look at the front page Boston Globe article that described
the most difficult MCAS question. The most difficult question on the 2001 math
test is a question involving probability and geometry, question 9 on the MCAS
test
http://www.doe.mass.edu/mcas/01release/
I've seen versio
Robert Dawson wrote:
> An obvious approach that would seem to give the advantages hoped for
>from the focussed test without the disadvantages would be just to group
>questions in the original test in roughly increasing order of
>difficulty. One might (I'm not so sure that this would be a go
At 01:57 PM 8/27/01 -0300, Robert J. MacG. Dawson wrote:
> The focussed test isn't an entirely bad idea; it does allow a
> genuine D
>student to avoid getting blown out of the water by questions intended to
>discriminate between A and B students. However, it seems like a very
>poor way t
> The focused test eliminates questions that would enable students to score A's,
> B's, and C's. All they get is another chance to score a D rather than an F.
> Implicit in the very concept of the focused test is the idea that a student who
> fails the standard MCAS test cannot be more than a D
On 27 Aug 2001 12:11:12 GMT, [EMAIL PROTECTED] (EugeneGall)
wrote:
> David Winsemius wrote
> >Here are the three stated competencies that the test is supposed to measure:
> >http://www.doe.mass.edu/mcas/01release/
I think it is legitimate for a class-room exam to offer
an item that rewards class
Dennis Robers wrote:
>eugene ... first of all ... how come your email ID always gets bounced
>back???
I added a nospam to the address to limit spam.
>now, certainly, you are not saying are you that if they "fail" this test
>the first time they take it in the 10th grade ... when it is given ... th
eugene ... first of all ... how come your email ID always gets bounced back???
now, certainly, you are not saying are you that if they "fail" this test
the first time they take it in the 10th grade ... when it is given ... they
cannot graduate, are you??? if that were the case ... these %ages b
David Winsemius wrote
>Here are the three stated competencies that the test is supposed to measure:
>http://www.doe.mass.edu/mcas/01release/
>1) Select, create, and interpret an appropriate graphical representation
>(e.g.,
>scatterplot, table, stem-and-leaf plots, box-and-whisker plots, circle
>gr
Before you decide how the test should be set up, and what should be on it, you
_must_ decide what you want the test result to do. Should sound a familiar
refrain to people who use statistics to answer questions and solve problems.
There are at least two options:
1)the test is a 'standards' f
Here are the three stated competencies that the test is supposed to measure:
http://www.doe.mass.edu/mcas/01release/
1) Select, create, and interpret an appropriate graphical representation
(e.g.,
scatterplot, table, stem-and-leaf plots, box-and-whisker plots, circle
graph, line
graph, and line pl
Since there were six questions regarding statistics on the test, I'd like to
see what questions those members of the mailing list might propose rather
than the six that were used.
Dr. Robert C. Knodt
4949 Samish Way, #31
Bellingham, WA 98226
[EMAIL PROTECTED]
"The man who does not read good bo
the first hurdle an item has to pass is ... a content one ... is the
content that we are asking about ... in the item ... sensible ... important
enough ... to spend 1 of the 6 items worth on the test ... given all the
concepts that could be tested on the test
if the answer to this is yes ... t
Hello Dennis and All --
Please pardon the formatting of my response here -- apparently I cannot
choose a different font, so I will bracket my comments by "-->" and "<---."
Dennis writes...
since i was not the person posting the original item on this matter ... i
do know in fact what the
At 10:40 AM 8/26/01 -0500, Olsen, Chris wrote:
>Dear Sir or Madam:
>
> I read with interest your posting on the issue of the so-called Tukey
>boxplot. I would like to make a few observations, if you will forgive the
>temerity of a high school teacher.
since i was not the person posting the ori
for a boxplot.
-- Chris
Chris Olsen
George Washington High School
2205 Forest Drive SE
Cedar Rapids, IA
(319)-398-2161
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]
Sent: Saturday, August 25, 2001 9:17 AM
To: [EMAIL PROTECTED]
Subject: Re: Boston Globe: MC
conceptually yes ... since, some items are clearly more important than
others ...
empirically ... since this has been explored many times ... back in the 70s
and 80s ... it seems to have no impact on rel and val ...
who decides? well, one way is to say ... experts ... have them rate items
in
In a message dated 8/25/01 9:06:18 AM Pacific Daylight Time, [EMAIL PROTECTED]
writes:
<< whether the item you talk about rises to the level of being important
enough ... i am not sure ... certainly, in the overall scheme of things ...
IF it is included ... it would have to be considered to
the only purpose it can serve ... and i am not saying this is important ...
is to know that the median is part of a boxplot ... just like you might
want them to identify what the | are at the ends ... the hinges ... just as
you might want them to know that the whisker has 25% in it ... at each
Some of the MCAS stats and probability questions were tough but fair. I
disagreed vehemently with one question:
Question 39 on the 10th grade Math 2001 test.
It showed a Tukey boxplot and asked whether the graph represented a mean and
range or a median and range.
Now, this question will do one
Leaving aside all questions about validity and usefulness of assessment
tests, the following article from front page of the Boston Globe shows
something about how much progress is needed in teaching basics of probability
and statistics at primary and secondary level. URL for the full article is
f
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