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3.2 Sampling Design
population
 the entire group of individuals we want information about
sample
 the part of the population that we actually examine in order to gather information
sample survey
 survey a sample to gain info about the population
voluntary response sample
 consists of people who choose themselves by responding to a general
appeal
(EX online polls)
Voluntary response samples are biased because people with strong opinions, especially negative
opinions, are most likely to respond.
simple random sample (SRS)
 SRS of size
n
consists of
n
individuals from the population chosen
in such a way that every set of
n
individuals has an equal chance to be the sample actually
selected
•SRS gives each individual an equal chance to be chosen
•SRS gives every possible sample of size
n
an equal chance to be chosen
systematic random sample
•systematic gives each individual an equal chance to be chosen
•systematic
not
give every possible sample of size
n
an equal chance to be chosen
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This note was uploaded on 10/13/2011 for the course PAM 2100 at Cornell University (Engineering School).
 '08
 ABDUS,S.

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