文档介绍:Definition of Statistics
Statistics is the study of variation, interactions and, operational definitions.
Statistics is the study of data to provide a basis for action on a population or process.
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Types of Statistical Studies
Enumerative studies are statistical investigations that lead to action on a static population (that is, a group of items, people, etc. that exist in a given time period and/or at a given location).
Analytic studies are statistical investigations that lead to action on a dynamic process.
Since this is a text on quality improvement, the primary focus will be on analytic studies.
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Enumerative Studies
Basic Concepts
A population (or universe) is the totality of units, items, or people of interest that exist in a given time period and/or given location Administration.
A frame is a list of the items in a population.
The gap is the difference between the frame and the population.
A sample is a portion of the frame under investigation, and is selected so that information can be drawn from it about the frame.
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Basic Concepts
Nonrandom samples are selected on the basis of convenience (convenience sample), the opinion of an expert (judgment sample), or a quota to ensure proportional representation of certain classes of items, units, or people in the sample (quota sample).
All nonrandom samples have the same shortcoming they're subject to an unknown degree of bias in their results.
This bias is caused by the absence of a frame.
Nonrandom samples should be used only when better information is too costly to obtain.
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Random samples are selected so that every element in the frame has a known probability of selection. Types of random samples include simple, stratified, and cluster.
All random samples allow generalized statements to be made about the frame from the sample.
A random sample is selected by operationally defining a procedure that utilizes random numbers in the selection of the sampled items from