Chapter 07

# Chapter 07 - for μ. (Exercise 7.10) x x x 2846 . 9 . 25 90...

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Inferences Based on a Single Sample: Estimation with Confidence Intervals

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Large-Sample Confidence Interval for a Population Mean How do we estimate the population mean and assess the estimate’s reliability? is an estimate of μ, and we use CLT to assess how accurate that estimate is. According to CLT, 95% of all from sample size n lie within 1.96σ of the mean Per the empirical rule, you can use 2 instead of 1.96 if you wish. x x
Large-Sample Confidence Interval for a Population Mean If is within 2σ of μ, then μ must be within 2σ of . We don’t know σ, so we’ll estimate it with s. n Consider a random sample of 90 observations that produces = 25.9 and s = 2.7. Find a 95% confidence interval

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Unformatted text preview: for μ. (Exercise 7.10) x x x 2846 . 9 . 25 90 7 . 2 2 9 . 25 2 ± = ± = ± n s x Small-Sample Confidence Interval for a Population Mean If n < 30, then there are two problems. is not “normal enough” to use Z scores. s is not as good of an estimate of σ. n In this case, we use t, a mound shaped distribution similar to Z, to compensate. Using the t-distribution yields larger intervals. df = n - 1 x Large-Scale Confidence Interval for a Population Proportion is a sample proportion [ statistic ] n p is the population proportion [ parameter ] n is normally distributed [ Use Z. ] p ˆ p ˆ n pq p p p = = ˆ ˆ σ μ...
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## This note was uploaded on 04/17/2008 for the course STAT 110 taught by Professor Pace during the Fall '07 term at Winona.

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Chapter 07 - for μ. (Exercise 7.10) x x x 2846 . 9 . 25 90...

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