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Unformatted text preview: Sections 4.4 and 4.5 Page 1 Inference for Two Independent Samples The goal is compare two means for two independent samplesgroups are independent. Assumptions h We have two samples from independent populations. h We will assume samples came from normal populations. Examples h Treatment vs. Control h What else? We want to estimate g G g using G ~ , (1- )x100% Confidence Interval When we know and When we do not know and Estimating the degrees of freedom for t If then 2 If unequal then Sections 4.4 and 4.5 Page 2 Example. An independent consumer group tested radial tires from two major brands to determine whether there were any differences in the expected tread life (thousands of miles). Brand g G 1 15 52 4.61 2 15 57 4.83 Construct and estimate the 95% for the mean difference. The estimated degrees of freedom is 27 How to test for equal variances...
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- Spring '10
- Statistics, Null hypothesis, Statistical hypothesis testing, radial tires, independent consumer group