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# class03_13 - 1.017/1.010 Class 13 Populations and Samples...

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1.017/1.010 Class 13 Populations and Samples Sampling and Repeated Trials: Statistics relies on sets of observations of random variables, commonly called samples . A sample can be viewed as a collection of outcomes from repeated trials . Random trial i yields an outcome (a particular number) corresponding to an underlying random variable x i . The collection of random variables associated with a sample of N observations is [ x 1 , x 2 , x 3 , …, x N ]. Samples are used to estimate distributional properties of the underlying random variables or to make inferences about relationships among different variables. Samples are sometimes supposed to be drawn from a larger population of (which may actually exist or may be hypothesized). Example: Define the random variable x to be the height of an MIT student drawn at random from the population of all MIT students. Suppose we record the heights of 10 MIT students selected at random. This can be viewed as a composite experiment composed of 10 repeated trials with 10

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## This note was uploaded on 11/29/2011 for the course CIVIL 1.00 taught by Professor Georgekocur during the Spring '05 term at MIT.

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class03_13 - 1.017/1.010 Class 13 Populations and Samples...

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