September 7, 2010
University of Phoenix
Central Limit Theorem and Confidence Intervals Problem Sets
Chapter 8 Exercises:
21. What is sampling error? Could the value of the sampling error be zero? If it were zero, what would this mean?
* Sampling error is the difference between the statistic estimated from a sample and the true population statistic. It is not impossible for the sampling error to not be zero. If the sampling error is zero then the population is uniform. For example if I were evaluating the ethnicities of a populations and everyone is the population was Black then taking any sample would give me the true proportion of 100% Black.
22. List the reasons for sampling. Give an example of each reason for sampling.
* The population size is too large and costly for making the study feasible in reasonable period.
For example, if I want to know how watching the violent shows on television affects the behavior of children, it won’t be realistic to study each child in the population, so I would use sampling.
* Only estimation of particular section of population is required
For example, if I want to take an example of nation which is combined unit of states. I can choose the random samples of states which can be further divided into smaller units like cities. These cities can be clustered into smaller areas for observation. Researchers can define his pattern of selecting the sample data until data condition of observation is fully satisfied.
* It is not possible to study the entire population and accessibility of them is time consuming and difficult
For Example, if I wanted to prepare a list of all the customers from a chain of hardware stores. This would be a tedious task. But it is convenient to choose a subset of stores in stage one of cluster sampling which can be used for interviewing the customers from those stores in... [continues]
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