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Ebook Even you can learn statistics (2nd edition): Part 2

(BQ) Part 2 book "Even you can learn statistics" has contents: Hypothesis testing - Chi-Square tests and the one way analysis of variance; simple linear regression; multiple regression; quality and six sigma applications of statistics,.and other contents. | Chapter 8 Hypothesis Testing: Z and t Tests 8.1 Testing for the Difference Between Two 8.2 8.3 Proportions Testing for the Difference Between the Means of Two Independent Groups The Paired t Test Important Equations One-Minute Summary Test Yourself In Chapter 7, you learned the fundamentals of hypothesis testing. This chapter discusses hypothesis tests that involve two groups, more formally known as two-sample tests. You will learn to use: • The hypothesis test that examines the differences between the proportions of two groups • The hypothesis test that examines the differences between the means of two groups You will also learn how to evaluate the statistical assumptions about your data that need to be true in order to use these tests and what to do if the assumptions do not hold. 8.1 Testing for the Difference Between Two Proportions Hypothesis test that analyzes differences between two groups by examining the proportion of items in each group that are in a particular category. CONCEPT From the Library of Gayle M. Noll 154 CHAPTER 8 HYPOTHESIS TESTING: Z AND t TESTS INTERPRETATION For this test, the test statistic is based on the difference in the sample proportion of the two groups. Both the sample proportion of occurrences in group 1 and the sample proportion of occurrences in group 2 are needed to perform this test. With a sufficient sample size in each group, the sampling distribution of the difference between the two proportions approximately follows a normal distribution (see Section 5.3). WORKED-OUT PROBLEM 1 The following two-way table summarizes the results of a study that investigated the manufacture of silicon wafers. This table presents the joint responses of whether a specific wafer was “good” or “bad” and whether that wafer had particles present on it. Counts of Particles Found Cross-Classified by Wafer Condition Wafer Condition Good Bad Total Yes 14 36 50 No 320 80 400 Total Particles Present 334 116 450 Of 334 wafers .