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Unformatted text preview: Week 6: Confidence Intervals l Inferential Statistics l Introduction to Estimation Statistics are used to make inferences about a population from a sample. Inferential Statistics Samples and Populations l “ … experience by way of sampling helps us make decisions about our environment … we rarely have complete control or full information before we make decisions.” l Sampling is a method that helps us make decisions about a population Statistical Methods Descriptive Statistics Inferential Statistics Statistical Methods l Involves – Estimation – Hypothesis testing l Purpose – Make decisions about population characteristics Population? Inferential Statistics Population Sample Sample statistic ( f8e5 X , Ps ) Estimates & tests Inference Process Estimating Parameters Point Estimate DEFINITION: A point estimate is a single value estimate for a population parameter. The best point estimate of the population mean is the sample mean . x Example: Point Estimate A random sample of airfare prices (in dollars) for a oneway ticket from Atlanta to Chicago. Find a point estimate for the population mean, . 99 102 105 105 104 95 100 114 108 103 94 105 101 109 103 98 96 98 104 87 101 106 103 90 107 98 101 107 105 94 111 104 87 117 101 The sample mean is 101.77 35 3562 n Σx x = = = The point estimate for the price of all one way tickets from Atlanta to Chicago is $101.77. An interval estimate is an interval, or range of values used to estimate a population parameter • 101.77 Point estimate ( ) • 101.77 The level of confidence, c, is the probability that the interval estimate contains the population parameter Interval Estimates z...
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 Spring '10
 Wright
 Statistics

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