Inferences on Two Populations

G baker department of statistics g university of

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Unformatted text preview: e to assume that the variances are equal. G. Baker, Department of Statistics G. University of South Carolina; Slide 13 Difference Between Means: µ1 – µ2 Difference Pooling Variances Standard Error: Standard sp 11 + n1 n2 where sp = 2 (n1 − 1) s1 2 + (n2 − 1) s2 n1 + n2 − 2 G. Baker, Department of Statistics G. University of South Carolina; Slide 14 Difference Between Means: µ1 – µ2 Difference Pooling Variances (1-α)100% CI: (1 Test Statistic: Test y1 − y2 ± tα / 2 s p 11 + n1 n2 ( y1 − y2 ) − ( µ1 − µ 2 ) 0 t= 11 + sp n1 n2 t has df = n1 + n2 -2 G. Baker, Department of Statistics G. University of South Carolina; Slide 15 Two Samples from Independent Populations An independent consumer group tested radial tires from two major brands to determine whether there was any difference in the average tread life (thousands of miles). The summary data is below: summary Brand n Sample mean Sample Stdev 1 15 52 4.61 2 15 57 4.83 Estimate the mean difference between the two G. Baker, Departme...
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