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NOTES_Chapter 13_Inference About Comparing Two Populations

# NOTES_Chapter 13_Inference About Comparing Two Populations...

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Chapter 13: Inference About Comparing Two Populations 13.1 Inference about the Difference between Two Means: Independent Samples Sampling Distribution of 1. is normally distributed if the populations are normal and approximately normal if the populations are nonnormal and the sample sizes are large. 2. The expected value of is 3. The variance of is The standard error of is Equal-Variances Test Statistic and Confidence Interval Estimator o Test Statistic When Where The quantity is called the pooled variance estimator . It is the weighted average of the two sample variances with the number of degrees of freedom in each sample used as weights. o Confidence Interval Estimator of When Unequal-Variances Test Statistic
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Unformatted text preview: and Confidence Interval Estimator o Test Statistic When o Confidence Interval Estimator of When • Testing the Population Variances o The hypotheses to be tested are o The test statistic is the ratio of the sample variances , which is F-distributed with degrees of freedom and . The required condition is the same as that for the t-test of , which is that both populations are normally distributed. o This is a two tail test so that the rejection region is o 13.2 Observational and Experimental Data 13.3 Inference about the Difference between Two Means: Matched Pairs Experiment 13.4 Inference about the Ratio of Two Variances 13.5 Inference about the Difference between Two Population Proportions...
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