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Unformatted text preview: lecture 22, Statistical Inferences Based on Two Samples Comparing Two Population Means by Using Independent Samples: Variances Known zBased Confidence Interval for the Difference in Means (Variances Known) zBased Test About the Difference in Means (Variances Known) Comparing Two Population Means by Using Large, Independent Samples: Variances lecture 22, Statistical Inferences Based on Two Samples Outline 1 Comparing Two Population Means by Using Independent Samples: Variances Known zBased Confidence Interval for the Difference in Means (Variances Known) zBased Test About the Difference in Means (Variances Known) 2 Comparing Two Population Means by Using Large, Independent Samples: Variances Unknown zBased Confidence Interval for the Difference in Means (Large Samples, Variances Unknown) zBased Test About the Difference in Means (Large Samples, Variances unknown) 3 Comparing Two Population Proportions by Using Large, Independent Samples lecture 22, Statistical Inferences Based on Two Samples Comparing Two Population Means by Using Independent Samples: Variances Known zBased Confidence Interval for the Difference in Means (Variances Known) zBased Test About the Difference in Means (Variances Known) Comparing Two Population Means by Using Large, Independent Samples: Variances lecture 22, Statistical Inferences Based on Two Samples Comparing Two Population Means by Using Independent Samples: Variances Known • Business improvement often requires making comparisons • Example • compare different types of advertising campaigns • compare the profitability of different investment portfolios • compare different production methods • ... • In this lecture • We discuss using confidence intervals and hypothesis tests to compare two populations. • We compare two population means and two population proportions by studying differences. lecture 22, Statistical Inferences Based on Two Samples Comparing Two Population Means by Using Independent Samples: Variances Known zBased Confidence Interval for the Difference in Means (Variances Known) zBased Test About the Difference in Means (Variances Known) Comparing Two Population Means by Using Large, Independent Samples: Variances lecture 22, Statistical Inferences Based on Two Samples Comparing Two Population Means by Using Independent Samples: Variances Known Sampling Distribution of the Difference of Two Sample Means • Suppose population 1 has mean μ 1 and variance σ 2 1 • From population 1, a random sample of size n 1 is selected which has mean ¯ x 1 and variance s 2 1 . • Suppose population 2 has mean μ 2 and variance σ 2 2 • From population 2, a random sample of size n 2 is selected which has mean ¯ x 2 and variance s 2 2 ....
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 Fall '09
 AnthonyChan

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