Credit-Quiz-Ch1-Key

# Credit-Quiz-Ch1-Key - KEY to BUS-271 In-class Quiz over...

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KEY to BUS-271 In-class Quiz over Chapter 1 2011-08-25 [Over 54 points] 102. [Chapter 1; 6 points] (Definitions) Explain the difference between a “population” and a “sample”. Does this distinction reside in the data, or does it depend on how we plan to use the data? To answer the second question first: the distinction is not found in the data, but in the use to which we want to put the data. (If I hand you a data set for 200 people and ask whether you can tell if this is a sample or a population, you can’t …) If the group of entities we want to ask questions about is limited to the entities which contributed data to the data set, then the data set is a population data set (a census). Example: I want to know the average height for members of this class , so I measure everybody’s height. If we want to ask questions about a group that’s bigger than the group which contributed data, then the data set is a sample data set. Example: I want to use class data to estimate the average height for all SUSCC students. (Note: For our data sample to be a valid sample, the group which contributed the data must be part of (a subset of) the intended population!) 103. [Chapter 1; 3 points] (Definitions) Define what we mean by an “outlier.” Why do we care about outlier s? An “outlier” is a data value that is very small or very large: it is “far from” the mean by some measure or other. (We have discussed 2 different ways of identifying outliers.) We worry about outliers because they

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Credit-Quiz-Ch1-Key - KEY to BUS-271 In-class Quiz over...

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