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Unformatted text preview: Click to edit Master subtitle style Determining How to Select a Sample Ch 12 Ch 12 22 Basic Concepts in Sampling • Population: the entire group under study as defined by research objectives – Researchers define populations in specific terms such as “heads of households located in areas served by the company who are responsible for making the pest control decision.” Ch 12 Ch 12 33 Basic Concepts in Sampling • Sample: a subset of the population that should represent the entire group • Sample unit: the basic level of investigation • Census: an accounting of the complete population Ch 12 Ch 12 44 Basic Concepts in Sampling • Sampling error: any error in a survey that occurs because a sample is used • A sample frame: a master list of the entire population • Sample frame error: the degree to which the sample frame fails to account for all of the population…a telephone book listing does not contain unlisted numbers Ch 12 Ch 12 55 Reasons for Taking a Sample • Practical considerations such as cost and population size • Inability of researcher to analyze huge amounts of data generated by census • Samples can produce precise results Ch 12 Ch 12 66 Two Basic Sampling Methods • Probability samples: ones in which members of the population have a known chance (probability) of being selected into the sample • Nonprobability samples: instances in which the chances (probability) of selecting members from the population into the sample are unknown Ch 12 Ch 12 77 Probability Sampling Methods • Simple random sampling • Systematic sampling • Cluster sampling • Stratified sampling Ch 12 Ch 12 88 Probability Sampling Methods Ch 12 Ch 12 99 Probability Sampling: Simple Random Sampling • Simple random sampling: the probability of being selected into the sample is “known” and equal for all members of the population – E.g., Blind Draw Method – Random Numbers Method (see MRI 12.1, p. 335) Ch 12 Ch 12 1010 Probability Sampling: Simple Random Sampling – Advantage: • Known and equal chance of selection – Disadvantages: • Complete accounting of population needed • Cumbersome to provide unique designations to every population member Ch 12 Ch 12 1111 Probability Sampling Systematic Sampling • Systematic sampling: way to select a random sample from a directory or list that is much more efficient than simple random sampling – Skip interval=population list size/sample size Ch 12...
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This note was uploaded on 04/14/2009 for the course MKT 232 taught by Professor Staff during the Spring '08 term at Illinois State.
 Spring '08
 Staff
 Marketing

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