In article <Ce7%8.15841$Fq6.1704086 at news2.west.cox.net> "John Knight" <johnknight at usa.com> writes:
<"Jet" <thatjetnospam at yahoo.com> wrote in message
<news:3D38D020.BE716AC0 at yahoo.com...
<> Cary Kittrell wrote:
<> > On any given question, all who answer can be assigned to one of three
<> > populations:
<> >
<> > P1, who knew the answer cold
<> > P2, who thought they did -- incorrectly
<> > P3, who guessed
<> >
<> > and John's method of subtracting 1/N * 100 percentage points from the
<> > entire group on each multiple choice question (N > 1) implicitly
<> > assigns the entire population to group P3, the one which guessed.
<> > This under-represents the contribution of group P1, who knew the
<> > answer, and even manages to under-represent the contribution of P2,
<> > the group which confidently put down the wrong answer -- and that
<> > explains why in John's analysis, on eight of twenty-eight items, he
<> > can claim that a negative number of girls got the question right.
<> > More girls answered incorrectly than actually took the test.
<>
<> LOL, exactly. And if he were using any of those extra brain cells of his
<> for thought, he'd realize that if he came to an improssible conclusion,
<> there is something wrong with the way he came to that concluison. But
<> he's just too stupid.
<>
<> >
<> > With this in mind, I hereby announce the next TIMSS test, which shall
<> > comprise exactly three questions:
<> >
<> > QUESTION 1) The current President of the United States, the man
<> > now sitting in the White House, is:
<> >
<> > a) George W. Bush
<> > b) Millard Fillmore
<> >
<> > comments: for all practical purposes, 100% of typical U.S.
<> > students will get this one right. Using John's approach, we next
<> > subtract 50 percentage points for guessing. The result is that
<> > John will now claim that only 50% of U.S. students got this
<> > question right. This example shows how John's method under-
<> > represents group P1.
<>
<> :) He won't get it.
<>
<> >
<> >
<> > QUESTION 2) Modern astronomy and phyics have shown that the Earth
<> > revolves around the Sun, and has discredited the more ancient
<> > idea that the Sun moved about the Earth.
<> >
<> > a) true
<> > b) false
<> >
<> > comments: only a handful of science nerds will get the right
<> > answer here (b); nearly all students will reflexively put down
<> > "a", which is wrong (no privileged frames of reference).
<>
<> And that holds the clue to the answer to H04, but even though I point
<> this out, John is still to .ucking stupid to get the answer right. :)
<>
<> > Essentially zero percent of students will get this one right. John
<> > will then subtract 50 percentage points for guessing, and report
<> > that MINUS 50% of students answered question two correctly, just
<> > as he got a minus score for eight of twenty-eight questions in the
<> > 12th grade girls example. The illustrates how John's method
<manages
<> > to under-represent even the zero-points contribution of group P2.
<>
<> :)
<>
<> >
<> > Question 3) How many species are there in the genus Crotalus?
<> >
<> > a) 26
<> > b) 27
<> >
<> > comments: except for a handful of herp fanatics, all students will
<> > guess on this one, giving a score of 50%. This is the only case
<> > in which an argument may be legitimately made for subtracting 50
<> > percentage points for guessing. This is group P3.
<> >
<> > (the correct answer is "b" -- assuming you're willing to accept
<> > that _Crotalus lannomi_, based on a single roadkill in Jalisco,
<> > is truly a new species of rattlesnake)
<> >
<> > So, we find that:
<> >
<> > question correct scoring John's method
<> >
<> > 1 100 50
<> > 2 0 - 50
<> > 3 0 0
<> >
<> > John's claim that "zero percent of American 12th grade girls solved
<> > simple math problems" implicitly assumes that all girls were guessing
<> > on all questions, which is completely unwarranted. This explains his
<> > puzzlement over why scores were lower than simple guessing would
<> > produce -- many did not guess, but he penalized them anyhow.
<>
<> He's a dolt. :)
<>
<> j
<>
<> >
<> > -- cary
<
<You're doing it all wrong, cary--which was to be expected, wasn't it?
<
<The correct way to compensate for gueses on multiple choice questions is to
<first calculate how many students would select each answer of a four part
<multiple choice question if they just guessed randomly. There's absolutely
<no way to get anything OTHER than 25% for each answer, A., B., C., and D.
<
<If the test designers equally distributed the correct answers over A., B.,
<C., and D. (which they did), then the correct answer will be selected 25% of
<the time (if all students just guessed at random).
<
<End of discussion. If you really believed this was wrong, you would have
<posted a correction months ago, but you didn't do that, did you?
<
<Some of the TIMSS multiple choice questions had 5 choices, in which event a
<completely random selection of these answers would result in each of A., B.,
<C., D., and E. being selected by 20% of the students, which means that 20%
<of all students would get the correct answer just by chance.
<
<Of the 39 TIMSS questions where both the scores and the original problems
<are available, American 12th grade girls set some kind of a record by
<selecting MORE wrong answers than if they'd just guessed on ONE THIRD of the
<questions. For example, H07 was a four part multiple choice question where
<at least 25% of them should have selected the right answer if they had just
<*guessed*, yet only 9.3% of them got it right
<http://christianparty.net/timssphysics.htm
<
<What would you call this, cary? How about "negative knowledge"? No other
<girls managed to score this low, yet American girls managed to secure that
<cherished dead last spot multiple times over. G04 was also a four part
<multiple choice question, yet only 21.6% of American girls got it right,
<which is 3.4% lower than if they'd just guessed. No other girls scored this
<low, and 54% of French girls DID get it correct. G08 was a five part
<multiple choice question, so 20% would have gotten it correct if they'd just
<guessed--yet only 10.9% of American girls got it correct, 9.1% less than if
<they'd just guessed. Yet half of Russian girls managed to get it correct.
<
<What in your expert opinion, cary, is responsible for such rampant "negative
<knowledge"?
<
Oh that's easy enough. My answer is:
QUESTION 1) The current President of the United States, the man
now sitting in the White House, is:
a) George W. Bush
b) Millard Fillmore
comments: for all practical purposes, 100% of typical U.S.
students will get this one right. Using John's approach, we next
subtract 50 percentage points for guessing. The result is that
John will now claim that only 50% of U.S. students got this
question right. This example shows how John's method under-
represents group P1.
QUESTION 2) Modern astronomy and phyics have shown that the Earth
revolves around the Sun, and has discredited the more ancient
idea that the Sun moved about the Earth.
a) true
b) false
comments: only a handful of science nerds will get the right
answer here (b); nearly all students will reflexively put down
"a", which is wrong (no privileged frames of reference).
Essentially zero percent of students will get this one right. John
will then subtract 50 percentage points for guessing, and report
that MINUS 50% of students answered question two correctly, just
as he got a minus score for eight of twenty-eight questions in the
12th grade girls example. The illustrates how John's method
manages
to under-represent even the zero-points contribution of group P2.
Question 3) How many species are there in the genus Crotalus?
a) 26
b) 27
comments: except for a handful of herp fanatics, all students will
guess on this one, giving a score of 50%. This is the only case
in which an argument may be legitimately made for subtracting 50
percentage points for guessing. This is group P3.
(the correct answer is "b" -- assuming you're willing to accept
that _Crotalus lannomi_, based on a single roadkill in Jalisco,
is truly a new species of rattlesnake)
So, we find that:
question correct scoring John's method
1 100 50
2 0 - 50
3 0 0
John's claim that "zero percent of American 12th grade girls solved
simple math problems" implicitly assumes that all girls were guessing
on all questions, which is completely unwarranted. This explains his
puzzlement over why scores were lower than simple guessing would
produce -- many did not guess, but he penalized them anyhow.
