April 2014
Intermediate to advanced
736 pages
20h 32m
English
Some basic properties of the sampling distribution of
can be expressed in terms of the population mean and variance when the observations form a random sample. Let
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In a random sample, the random variables X1, …, Xn are independent, and each has the distribution of the population. Consequently, each observation has mean μ and variance σ2, or
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Next,
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and n is a constant. Using the additivity properties of expectation and variance discussed in Appendix A3.4, we obtain

Furthermore, taking the square root yields
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