Discussion Question
Chapter 13 Sampling in Quantitative Research
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1
Question #1
Tell whether the following statement is true or false:
The aggregate of cases in which a researcher is interested is called a sample.
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Answer to Question #1
False
The aggregate of cases in which a researcher is interested is called a population. A sample is selection of a portion of the population to represent the entire population.
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Basic Sampling Concepts in Quantitative Studies #1
Population: the aggregate of cases in which a researcher is interested
Accessible population: the aggregate of cases that conform to designated criteria and that are accessible for a study
Target population: the aggregate of cases about which the researcher would like to generalize
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Basic Sampling Concepts in Quantitative Studies #2
Eligibility criteria/inclusive criteria: criteria that specify population characteristics
Cost
Practical constraints
People’s ability to participate
Design considerations
Exclusion criteria
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5
Basic Sampling Concepts in Quantitative Studies #3
Samples and Sampling
Sampling: selection of a portion of the population (a sample) to represent the entire population
Element: basic population unit about which information is collected
Sample: a subset of population elements
Representative sample
Probability sample
Nonprobability sample
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Question #2
Tell whether the following statement is true or false:
Researchers usually sample from the target population.
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Answer to Question #2
False
Researchers usually sample from the accessible population but should identify the target population to which they want to generalize their results.
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Basic Sampling Concepts in Quantitative Studies #4
Staged sample: samples are sometimes selected in multiple phases
Sampling bias: the systematic over- or underrepresentation of segments of the population on key variables
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Question #3
Tell whether the following statement is true or false:
Probability sampling involves random selection of elements.
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Answer to Question #3
True
Probability sampling involves random selection of elements.
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Nonprobability Sampling
Convenience sampling
Snowball sampling
Quota sampling
Consecutive sampling
Purposive sampling
Evaluation of nonprobability sampling
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Probability Sampling
Simple random sampling
Stratified random sampling
Multistage sampling
Cluster sampling
Systematic sampling
Evaluation of probability sampling
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13
Sample Size in Quantitative Studies
Power analysis
Estimate sample size
Large samples preferred to small samples
Sample size basics
Factors affecting sample size /requirements in quantitative research
Effect size
Homogeneity of the population
Cooperation and attrition
Subgroup analyses
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Implementing a Quantitative Sampling Plan
Steps in sampling
Identify the population
Specify the eligibility criteria
Specify the sampling plan
Recruit the sample
Sample recruitment
Screening instrument
Generalizing from samples
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Critical Appraisal of Sampling Plans #1
Sampling Plan
Construct
Internal factors
External factors
Statistical conclusion validity
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Critical Appraisal of Sampling Plans #2
Sampling plan should be scrutinized with respect to
Approach used
Study population and eligibility criteria
Number of participants and rationale for sample size
Inclusion of power analysis
Description of main characteristics of sample
Number and characteristics of participants who declined participation/dropped out
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