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Unformatted text preview: SUNY at Albany  Department of Economics Eco 320 • Economic Statistics From Sample to Population Sampling Distribution 1. The Big Idea of StatisticsSampling Distribution A. Choosing a random sample from a population and calculating a statistic such as sample mean is a random phenomenon. B. The sampling distribution of a statistic tells us what values the statistic takes in repeated samples from the same population and how often it takes those values. C. We think of a sampling distribution as assigning probabilities to the values the statistic can take. Because there are usually many possible values, sampling distributions are often described by a density curve such as a Normal curve. SUNY at Albany  Department of Economics Eco 320 • Economic Statistics [Example] Opinion on a Constitutional Amendment Revisited A. Take a random sample of 2527 adults. Ask each whether they favor a constitutional amendment that would define marriage as being between a man and a woman. The proportion who say “Yes” B. is the sample proportion . Do this 10000 times and collect the 10000 sample proportions from the 10000 samples. The histogram shows the distribution of 10000 when the truth about the population is that 50% would favor such an amendment. C. The results of random sampling are random : we can’t predict the outcome of one sample, but the figure shows that the outcomes of many samples have a regular pattern. SUNY at Albany  Department of Economics Eco 320 • Economic Statistics 2527 yes" " say number who ˆ p p ˆ p ˆ p ˆ [Example] Opinion on a Constitutional Amendment Revisited (cont’d) SUNY at Albany  Department of Economics Eco 320 • Economic Statistics [Example] Opinion on a Constitutional Amendment Revisited (cont’d) A. The regular pattern of repeated random samples is one of the big ideas of statistics....
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This note was uploaded on 02/08/2012 for the course ECON 320 taught by Professor Chan during the Spring '11 term at SUNY Albany.
 Spring '11
 Chan
 Economics

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