STA 200 chapter2

STA 200 chapter2 - Chapter 2 Good Sampling and Bad Sampling...

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Chapter 2 Good Sampling and Bad  Sampling
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Famous Example of Bad  Sampling In 1936, the  Literary Digest  ran a poll which  predicted a victory for Alf Landon over  Franklin D. Roosevelt in the presidential  election.   The  Literary Digest  sent out 10 million  ballots, of which 2.3 million were returned.   The ballots were sent to  Literary Digest  readers, as well as households listed in  telephone books and automobile registration  records.
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Terminology A statistical study is  biased  if certain  outcomes are statistically favored. voluntary response sample  is a sample  that chooses itself by responding to a general  appeal.  Voluntary response samples will be  present with write-in and call-in polls. Note:  People with strong opinions (especially  negative ones) tend to have a high response  rate.
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Bias People with strong opinions (especially  negative ones) tend to have a high response  rate. Thus, in a voluntary response sample, those  opinions will tend to be statistically favored. In other words, the poll will be biased, and 
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This note was uploaded on 04/17/2008 for the course STA 200 taught by Professor Wierdhobbitguy during the Spring '08 term at Kentucky.

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STA 200 chapter2 - Chapter 2 Good Sampling and Bad Sampling...

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