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AP Statistics Thursday, 10 April 2014 • OBJECTIVE TSW (1) quiz over two-sample inference and (2) review for tomorrow’s test covering two-sample inference. • ASSIGNMENT DUE – WS Mixed Hypothesis Review #1 wire basket • QUIZ: 2-Sample Inference – Means & Proportions will be given momentarily. • TEST: Two-Sample Inference is tomorrow. WS: Two-Sample Inference with Means #1 1) (32.494, 40.799) We are 95% confident that the true difference in mean sugar content between children and adult cereals is between 32.494% and 40.799%. 2) t = 1.406 p-value = 0.0801 df = 590.049 Fail to reject 3) (–0.2898, 1.7378) Since 0 is in the interval, there is not evidence of a difference. WS: Two-Sample Inference with Means #1 4) t = 2.478 p-value = 0.01509 Fail to reject H0. 5) Type I error df = 90.486 WS: Two-Sample Inference with Means #2 1) Normal distribution, μpu – pe = 16 – 14 = 2 lbs pu – pe = 0.72/15 + 0.52/15 = 0.2221 lbs 2) P( (x-barpu – pe) < 1.8) = 0.1839 3) P(1.5 < (x-barpu – pe) < 2.5) = 0.9756 4) 40th %’ile = 1.9437 lbs 5) 95th %i’le = 2.3653 lbs QUIZ: 2-Sample Inference Means & Proportions Checkerboard, please ! Test Topics: Two-Sample Inference Testing • Know the pooling pˆ formula. x1 x2 pˆ n1 n2 • Compute confidence intervals for differences in means. • Compute confidence intervals for differences in proportions. • Know the conditions for using z-tests and t-tests. • Know your assumptions! Test Topics: Two-Sample Inference Testing • Identify Type I and Type II errors. • State conclusions: – Confidence intervals: “We are < >% confident that …” – Hypothesis tests: “p < > , so we reject/fail to reject …” • Know the formula for calculating a z-test statistic for hypothesis testing. pˆ1 pˆ2 1 1 pˆ 1 pˆ n n 1 2 Test Topics: Two-Sample Inference Testing • Know the relationship between power and . • Compute sample sizes for given confidence intervals. • Compute standard error. • Know the characteristics of a matched-pairs test. • Perform a full two-sample proportion hypothesis test. WS AP Mixed Review: Two-Sample Inference 1. E 9. E 2. B 10. A 3. B 11. D 4. D 12. C 5. C 13. A 6. E 14. C 7. E 15. A 8. D 16. B