[cc'd to previous poster]
Rich Ulrich <[EMAIL PROTECTED]> wrote in sci.stat.edu:
>I think I could not blame students for floundering about on this one.
>
>On Thu, 29 Nov 2001 14:39:35 -0500, [EMAIL PROTECTED] (Stan Brown)
>wrote:
>> "The manufacturer of a patent medicine claims that it is 90%
>> effective(*) in relieving an allergy for a period of 8 hours. In a
>> sample of 200 people who had the allergy, the medicine provided
>> relief for 170 people. Determine whether the manufacturer's claim
>> was legitimate, to the 0.01 significance level."
>I have never asked that as a question in statistics, and
>it does not have an automatic, idiomatic translation to what I ask.
How would you have phrased the question, then? Though I took this
one from a book, I'm always looking to improve the phrasing of
questions I set in quizzes and exams.
>I can expect that it means, "Use a 1% test." But, for what?
>That claim could NEVER, legitimately, have been *based*
>on these data. That is an idea that tries to intrude itself,
>to me, and makes it difficult to address the intended question.
Agreed! My idea, in reading that problem, was that the manufacturer
claimed something for a product that has been on the market for some
time, and some independent group, such as a newspaper or TV network,
did a study to test the claim.
> - By the way, it also bothers me that "90% effective" is
>apparently translated as "effective for 90% of the people."
>I wondered if the asterisk was supposed to represent "[sic]".
The asterisk led to my note defining it as relieving symptoms for
90% of people who use it, and asking students to think whether the
claim would also be true if it relieved symptoms for more than 90%.
(I think the real-world answer is clearly Yes: If a product is
claimed to help 90% of people and it actually helps 93%, we do not
say the claim was false.)
--
Stan Brown, Oak Road Systems, Cortland County, New York, USA
http://oakroadsystems.com
My reply address is correct as is. The courtesy of providing a correct
reply address is more important to me than time spent deleting spam.
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