Definition
Suppose there is a fixed parameter that needs to be estimated. Then an "estimator" is a function that maps the sample space to a set of sample estimates. An estimator of is usually denoted by the symbol . It is often convenient to express the theory using the algebra of random variables: thus if X is used to denote a random variable corresponding to the observed data, the estimator (itself treated as a random variable) is symbolised as a function of that random variable, . The estimate for a particular observed dataset (i.e. for X=x) is then, which is a fixed value. Often an abbreviated notation is used in which is interpreted directly as a random variable, but this can cause confusion.
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“The very definition of the real becomes: that of which it is possible to give an equivalent reproduction.... The real is not only what can be reproduced, but that which is always already reproduced. The hyperreal.”
—Jean Baudrillard (b. 1929)
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—Adrienne Rich (b. 1929)
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—Elaine Heffner (20th century)