Chapter 9. Comparing Two Means

9.1 Introduction 224

9.1.1 Hypotheses for Comparing Two Means 224

9.1.2 Paired t-Test versus Two-Sample t-Test 225

9.2 Two-Sample t-test 227

9.2.1 Detail Example: Comparing Processor Speeds of Two Brands 228

9.2.2 Two-Sample t-test in JMP 230

9.2.3 Interpretation of Two-Sample Results 232

9.3 Paired t-test 233

9.3.1 Detail Example: Advertising Effect in Test Markets 234

9.3.2 Paired t-test in JMP 236

9.3.3 Interpretation of Paired t-test Results 237

9.4 Paired t-test versus Two-Sample t-test on the Same Data 238

9.4.1 Example: Abrasion Resistance 238

9.4.2 Summary of Differences between the Paired and Two-Sample t-test 240

9.5 Summary 241

9.6 Problems 241

9.7 Case Study: Westville Meat Processing Plant 244

9.8 References 246