Chapter 7

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Chapter 7 - PowerPoint PPT Presentation

Chapter 7. The Logic Of Sampling Key Terms. Nonprobability sampling Technique in which samples are selected in a way that is not suggested by probability theory.

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Chapter 7

The Logic Of SamplingKey Terms

Nonprobability samplingTechnique in which samples are selected in a way that is not suggested by probability theory.
Purposive (judgmental) samplingSelecting a sample based on the knowledge of a population, it's elements and the purpose of the study.
Snowball samplingResearcher collects data on members of the target population that can be located, then asks those individuals to provide the information to locate other members.
Quota samplingUnits are selected into a sample on the basis of prespecified characteristics, so the total sample will have the same distribution of characteristics assumed to exist in the population being studied.
Probability samplingSamples are selected in accord with probability theory, typically involving some random selection mechanism.
RepresentativenessQuality of a sample having the same distribution of characteristics as the population from which it was selected.
EPSEMEqual probability of selection method.
• ElementUnit about which information is collected and that provides the basis of analysis.
• Study populationAggregation of elements from which the sample is actually selected.
Random selectionEach element has an equal chance of selection independent of any other event in the selection process.
• Sampling unitElement or set of elements considered for selection in some stage of sampling.
• StatisticSummary description of a variable in a sample.
• Confidence levelExpression of the accuracy of sample statistics.
Confidence intervalRange of values within which a population parameter is estimated to lie.
• Sampling frameList or quasi list of elements from which a probability sample is selected.
Simple random samplingBasic sampling method assumed in the statistical computations of social research.
• Systematic samplingEvery kth element in the total list is chosen for inclusion in the sample.
• Sampling ratioProportion of elements in the population that are selected.
Cluster samplingA multistage sampling in which natural groups are sampled initially with the members of each selected group being subsampled afterward.
PPSProbability proportionate to size.
• WeightingGiving some cases more weight than others.