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All of Statistics: A Concise Course in Statistical Inference. Chapter 3 Expectation Prepared by Gene Shiau. The average value of X. Also known as the expectation the mean the first moment The k th moment of X is. Properties of expectations.
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All of Statistics:A Concise Course inStatistical Inference Chapter 3 Expectation Prepared by Gene Shiau
The average value of X • Also known as • the expectation • the mean • the first moment • The kth moment of X is
Properties of expectations • If X1, ..., Xn are random variables and a1, ..., an are constants, then • If X1, ..., Xn are independent random variables, then
The spread of X • Commonly measured using • the variance • If X has mean , the variance of X is • A well defined variance has the following properties:
Sample statistics • The sample mean is • The sample variance is • Let X1, …, Xn be independent identically distributed, then
The covariance and correlation • The covariance • The correlation
Conditional expectation • The conditional variance is
Laplace transform of X • Also known as • the moment generating function (MGF) • Properties: