Re: Statistical illiteracy: more examples
Here are the Forsooth items from the latest Chance News: Migraines affect approximately 14% of women and 7% of men; that's one fifth of the population. Herbal Health Newsletter Issue 1 undated Nine out of ten people said that health was the most important issue in the election; four out of ten said Europe was the most important issue. BBC Radio 5 Breakfast Programme 29 May 2001 Between 1974 and the end of 2000 the [pulp and paper] industry underperformed the overall European market by a shocking 914% The Economist 15 September 2001 (For those unfamiliar with it, Chance News is an email newsletter for those interested in the Chance course on prob/stat -- it's a great source for prob/stat topics in the news.) http://www.dartmouth.edu/~chance Jill Binker Fathom Dynamic Statistics Software KCP Technologies, an affiliate of Key Curriculum Press 1150 65th St Emeryville, CA 94608 1-800-995-MATH (6284) [EMAIL PROTECTED] http://www.keypress.com http://www.keycollege.com __ = Instructions for joining and leaving this list, remarks about the problem of INAPPROPRIATE MESSAGES, and archives are available at http://jse.stat.ncsu.edu/ =
Re: Statistical illiteracy
On Wed, 26 Dec 2001 [EMAIL PROTECTED] wrote (edited): I came across a table of costume jewelry at a department store with a sign that said 150% off. I asked them how much they would pay me to take it all off of their hands. I had to explain to them what 150% meant, and they then explained to me how percentages are computed in the retail trade: first we cut the price in half (50%). Then we cut it in half again. Now we have cut it in half a third time. 50% + 50% + 50% = 150% off. ... ... if they advertise a 150% discount directly, without referring to the sequence of three 50% discounts, might they not be liable to legal action for misrepresentation? I would tell the clerk in the store, Ah, you get 150% off by taking 75%-off of 75%-off. I'll take it. (1/16 price vs. 50%-off 50%-off 50%-off =1/8 price). Why settle for 1/16? Take 60% off after 90% off. Or 55% after 95%. Or 50% after 100%, which ought to underline the illogic even for arithmetically illiterate retailers. -- DFB. Donald F. Burrill [EMAIL PROTECTED] 184 Nashua Road, Bedford, NH 03110 603-471-7128 = Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ =
Re: Statistical illiteracy
In [EMAIL PROTECTED] Donald Burrill wrote: On Wed, 26 Dec 2001 [EMAIL PROTECTED] wrote (edited): I came across a table of costume jewelry at a department store with a sign that said 150% off. I asked them how much they would pay me to take it all off of their hands. I had to explain to them what 150% meant, and they then explained to me how percentages are computed in the retail trade: first we cut the price in half (50%). Then we cut it in half again. Now we have cut it in half a third time. 50% + 50% + 50% = 150% off. ... ... if they advertise a 150% discount directly, without referring to the sequence of three 50% discounts, might they not be liable to legal action for misrepresentation? I would tell the clerk in the store, Ah, you get 150% off by taking 75%-off of 75%-off. I'll take it. (1/16 price vs. 50%-off 50%-off 50%-off =1/8 price). Why settle for 1/16? Take 60% off after 90% off. Or 55% after 95%. Or 50% after 100%, which ought to underline the illogic even for arithmetically illiterate retailers. -- DFB. Donald F. Burrill [EMAIL PROTECTED] 184 Nashua Road, Bedford, NH 03110 603-471-7128 This leads to a nice quiz question: what way of taking 150% off is most advantageous to the seller, and what is the most advantageous way for the buyer? Are there single optima or multiple or continuous optima, or none? (The answer will appear upside down at the bottom of the page ;-) -- == Lee Altenberg, Ph.D. E-mail: [EMAIL PROTECTED] == = Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ =
Re: Statistical illiteracy
I have to add a short story to this thread. As ateacher a local dry cleaning store gave teachers a 10% discount. I took some clothes to be cleaned and when I picked them up the total was $23.75. The clerk asked for that amount. I indicated that I was a teacher and would like the 10% discount. Without hesitation the clerk said, Certainly, that means you only have to pay $20.00. This took me back somewhat and I indicated that this was the wrong amount. The clerk wipped out a hand calculator, entered 23.75 and subtracted 3.75. He announced, No, that's the correct amount. Now I did something stupid. I tried to explain why it was wrong. The manager noticed our conversation, walked over and asked about the problem. The clerk indicated that I was entitled to 10% off the $23.75 price and that I felt that $20.00 was the wrong amount. The manager took the calculator, did exactly the same thing, arrived at $20.00 and then explained to the clerk. You don't need the calculator, simply move the decimal point one place to the left, drop what is on the right and move the decimal point back. See, move the decimal point so the amount is 2.375, drop the .375 and move the decimal point back so it becomes $20.00. Simple. Too simple for me. I took my clothes and left. A few weeks later I went back, left come clothes and when I picked them up the bill came to $28.50. You guessed it. It cost me $20.00. I couldn't resist and tried to explain the error to the clerk and manager again. No success and after about ten minutes the manager indicated that if I didn't want the discount then I shouldn't come to this store. Now the end of the story. After six months later the store closed its doors. Bankrupt. Need I say more? Oh yes, I'm not sure what they would have done if the pice had been $8.50. I guess I should had tried to find out if they would have given me the clothes for free. GOD BLESS AMERICA Dr. Robert C. Knodt 4949 Samish Way, #31 Bellingham, WA 98226 [EMAIL PROTECTED] Happiness comes through doors you didn't even know you left open. = Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ =
Re: Statistical illiteracy
In [EMAIL PROTECTED] Donald Burrill wrote: On Fri, 14 Dec 2001, Wuensch, Karl L wrote: I came across a table of costume jewelry at a department store with a sign that said 150% off. I asked them how much they would pay me to take it all off of their hands. I had to explain to them what 150% meant, and they then explained to me how percentages are computed in the retail trade: first we cut the price in half (50%). Then we cut it in half again. Now we have cut it in half a third time. 50% + 50% + 50% = 150% off. ... But back to your retail trade: if they advertise a 150% discount directly, without referring to the sequence of three 50% discounts, might they not be liable to legal action for misrepresentation? -- DFB. Donald F. Burrill [EMAIL PROTECTED] 184 Nashua Road, Bedford, NH 03110 603-471-7128 I would tell the clerk in the store, Ah, you get 150% off by taking 75%-off of 75%-off. I'll take it. (1/16 price vs. 50%-off 50%-off 50%-off =1/8 price). -- == Lee Altenberg, Ph.D. E-mail: [EMAIL PROTECTED] == = Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ =
RE: Statistical illiteracy
On Fri, 14 Dec 2001, Wuensch, Karl L wrote: I came across a table of costume jewelry at a department store with a sign that said 150% off. I asked them how much they would pay me to take it all off of their hands. I had to explain to them what 150% meant, and they then explained to me how percentages are computed in the retail trade: first we cut the price in half (50%). Then we cut it in half again. Now we have cut it in half a third time. 50% + 50% + 50% = 150% off. Interesting. Not altogether surprising, though. In a conversation with a local bank mortgage person, I explained that part of my income is in Canadian funds, deposited into my bank in Toronto, and the current exchange rate is (approximately) 1.50 (Canadian $ for each US $). She then wanted to calculate the equivalent US income by discounting the Canadian value by 50%. I pointed out that this was incorrect: one would discount the Canadian value by 33%. She said I hear what you're saying, but went on to indicate that it somehow wasn't relevant. I could not tell whether (a) she didn't believe me, (b) she didn't know how to deal with the arithmetic of exchange rates, (c) this is the way we do it here, (d) something else, or (e) a combination of the above. Whatever the case, I decided it would be the better part of valor to deal with another bank. But back to your retail trade: if they advertise a 150% discount directly, without referring to the sequence of three 50% discounts, might they not be liable to legal action for misrepresentation? -- DFB. Donald F. Burrill [EMAIL PROTECTED] 184 Nashua Road, Bedford, NH 03110 603-471-7128 = Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ =
Re: Statistical illiteracy in Assoc. Press
On Fri, 14 Dec 2001, Jill Binker wrote:
If remark about putting numbers on a single line is referring to:
They record the results of their mental calculations using a
horizontal format. For example, 86+57=86+50+7=136+7=143.
Then I see nothing wrong with this (and it has NOTHING to do with what
sorts of paper you bank will be sending you -- you're confusing purposes
here: what configuration helps young children learn v. what's the most
efficient way to present the story of the ebb and flow of my money).
...
Jill Binker
Fathom Dynamic Statistics Software
KCP Technologies, an affiliate of
Key Curriculum Press
1150 65th St
Emeryville, CA 94608
1-800-995-MATH (6284)
[EMAIL PROTECTED]
http://www.keypress.com
http://www.keycollege.com
__
Sorry. You're right of course about the need for intuitive understanding.
I think I was particularly grouchy after a tough term, and too many
attempts to explain to students that in some circumstances about right
is not good enough, and that by starting and proceeding logically and
carefully they could be exactly right, often with less effort.
J.E.H.Shaw [Ewart Shaw][EMAIL PROTECTED] TEL: +44 2476 523069
Department of Statistics, University of Warwick, Coventry CV4 7AL, U.K.
http://www.warwick.ac.uk/statsdept/Staff/JEHS/
3 ((4({*.(=+/))++/=3:)@([:,/0,^:(i.3)@|:2^:2)).@]^:(i.@[) #:3 6 2
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RE: Statistical illiteracy
Don asked: But back to your retail trade: if they advertise a 150% discount directly, without referring to the sequence of three 50% discounts, might they not be liable to legal action for misrepresentation? Perhaps in the distant past, when our government attempted to protect the rights of consumers, but things seem a lot different now. ;-) Karl W. = Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ =
Re: Statistical illiteracy in Assoc. Press
If remark about putting numbers on a single line is referring to:
They record the results of their mental calculations using a
horizontal format. For example, 86+57=86+50+7=136+7=143.
Then I see nothing wrong with this (and it has NOTHING to do with what
sorts of paper you bank will be sending you -- you're confusing purposes
here: what configuration helps young children learn v. what's the most
efficient way to present the story of the ebb and flow of my money).
At 12:18 PM + 12/14/01, [EMAIL PROTECTED] () wrote:
I throw in the following quote from an article by Dea Birkett
on the National Numeracy Strategy (Guardian, Tuesday December 11)
[ see the link And counting on]
[ http://www.education.guardian.co.uk/higher/maths/ ]
Columns are the first casualty in this push for understanding.
Putting numbers underneath each other is a very useful skill
if the aim is to perform additions correctly, says Alan Graham,
lecturer in mathematical education at the Open University.
But if you put them on a single line you have to look at them
more intuitively.
I quiver with anticipation at the delightful prospect
of receiving a helpfully intuitive bank statement.
-- Ewart Shaw
--
J.E.H.Shaw [Ewart Shaw][EMAIL PROTECTED] TEL: +44 2476 523069
Department of Statistics, University of Warwick, Coventry CV4 7AL, U.K.
http://www.warwick.ac.uk/statsdept/Staff/JEHS/
3 ((4({*.(=+/))++/=3:)@([:,/0,^:(i.3)@|:2^:2)).@]^:(i.@[) #:3 6 2
Jill Binker
Fathom Dynamic Statistics Software
KCP Technologies, an affiliate of
Key Curriculum Press
1150 65th St
Emeryville, CA 94608
1-800-995-MATH (6284)
[EMAIL PROTECTED]
http://www.keypress.com
http://www.keycollege.com
__
=
Instructions for joining and leaving this list and remarks about
the problem of INAPPROPRIATE MESSAGES are available at
http://jse.stat.ncsu.edu/
=
Re: Statistical illiteracy in Assoc. Press
[EMAIL PROTECTED] wrote: Today's story from the Associated Press, Study: American kids getting fatter at disturbing rate. By 1998, nearly 22 percent of black children ages 4 to 12 were overweight, [] overweight. ...Overweight was defined as having a body-mass index higher than 95 percent of youngsters of the same age and sex, based on growth charts On its face, it seems to say 22% of black children ages 4 to 12 had body-mass-index greater than 95% of [their peers]. This is mind-bendingly difficult to comprehend as stated; but I think what they must have *meant* was 22% of black children ages 4 to 12 had body-mass-index in the greatest 5-th percentile of a *particular*, prior, distribution of body-mass-indices which was once considered representative of an acceptable state of affairs for the cohort of children 4-12. Is this what they meant? = Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ =
Statistical illiteracy in Assoc. Press
Today's story from the Associated Press, Study: American kids getting fatter at disturbing rate. By 1998, nearly 22 percent of black children ages 4 to 12 were overweight, as were 22 percent of Hispanic youngsters and 12 percent of whites. ...In 1986, the same survey showed that about 8 percent of black children, 10 percent of Hispanic youngsters and 8 percent of whites were significantly overweight. ...Overweight was defined as having a body-mass index higher than 95 percent of youngsters of the same age and sex, based on growth charts from the 1960s to 1980s. ... Disturbing trends also were seen in the number of children who had a body-mass index higher than 85 percent of their peers. In 1986, about 20 percent of blacks, Hipanics and whites alike were in that category. By 1998, those figures had risen to about 38 percent of blacks and Hispanics alike and nearly 29 percent of whites. I guess that means that today's children have gotten so fat, that 100% is not enough to account for them---in1986 children required105%, and by1998 a full 114% to123% was required to account for them ;-). The only way I can make sense out of this story is if these percentages use as a baseline the 50 percentile and 85 percentile body-mass index values from the 1960s. But clearly, neither the author, or the editors, either understood or cared that what they were writing was self-contradictory on its face. Can our statistical literacy have gotten that bad? It reminds me of the story that Barry Goldwater in his 1964 Presidential campaign vowed that if he were elected, no American would make less than the national average income. -- == Lee Altenberg, Ph.D. E-mail: [EMAIL PROTECTED] == = Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ =
