Inferences on Two Populations

# Baker department of statistics g university of south

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Unformatted text preview: σ2 n2 G. Baker, Department of Statistics G. University of South Carolina; Slide 4 (1-α)100% Confidence Interval on µ1 – µ2 Format for a (1-α)100% Confidence Interval based on a normal sampling distribution: Point Estimate + Distribution Value * Standard Error y1 − y2 ± zα / 2 σ 2 1 n1 + σ 2 2 n2 y1 − y2 ± tα / 2 2 1 2 2 s s + n1 n2 G. Baker, Department of Statistics G. University of South Carolina; Slide 5 Difference Between Means: µ1 – µ2 Difference Estimated Degrees of Freedom for t: Estimated 2 + n n 2 1 df = 2 2 2 2 s1 s2 1 1 + n1 − 1 n1 n2 − 1 n2 2 s1 2 s2 G. Baker, Department of Statistics G. University of South Carolina; Slide 6 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 with a 95% Confidence G Interval; degrees of freedom estimated...
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