Table of Content
Preface ix
Acknowledgments xi
Introduction xiii
1 Designing and Carrying Out a Statistical Study 1
1.1 A Small Example, 3
1.2 Is Chance Responsible? The Foundation of Hypothesis Testing, 3
1.3 A Major Example, 7
1.4 Designing an Experiment, 8
1.5 What to Measure–Central Location, 13
1.6 What to Measure–Variability, 16
1.7 What to Measure–Distance (Nearness), 19
1.8 Test Statistic, 21
1.9 The Data, 22
1.10 Variables and Their Flavors, 28
1.11 Examining and Displaying the Data, 31
1.12 Are we Sure we Made a Difference? 39
Appendix: Historical Note, 39
1.13 Exercises, 40
2 Statistical Inference 45
2.1 Repeating the Experiment, 46
2.2 How Many Reshuffles? 48
2.3 How Odd is Odd? 53
2.4 Statistical and Practical Significance, 55
2.5 When to use Hypothesis Tests, 56
2.6 Exercises, 56
3 Displaying and Exploring Data 59
3.1 Bar Charts, 59
3.2 Pie Charts, 61
3.3 Misuse of Graphs, 62
3.4 Indexing, 64
3.5 Exercises, 68
4 Probability 71
4.1 Mendel’s Peas, 72
4.2 Simple Probability, 73
4.3 Random Variables and their Probability Distributions, 77
4.4 The Normal Distribution, 80
4.5 Exercises, 84
5 Relationship between Two Categorical Variables 87
5.1 Two-Way Tables, 87
5.2 Comparing Proportions, 90
5.3 More Probability, 92
5.4 From Conditional Probabilities to Bayesian Estimates, 95
5.5 Independence, 97
5.6 Exploratory Data Analysis (EDA), 99
5.7 Exercises, 100
6 Surveys and Sampling 104
6.1 Simple Random Samples, 105
6.2 Margin of Error: Sampling Distribution for a Proportion, 109
6.3 Sampling Distribution for a Mean, 111
6.4 A Shortcut–the Bootstrap, 113
6.5 Beyond Simple Random Sampling, 117
6.6 Absolute Versus Relative Sample Size, 120
6.7 Exercises, 120
7 Confidence Intervals 124
7.1 Point Estimates, 124
7.2 Interval Estimates (Confidence Intervals), 125
7.3 Confidence Interval for a Mean, 126
7.4 Formula-Based Counterparts to the Bootstrap, 126
7.5 Standard Error, 132
7.6 Confidence Intervals for a Single Proportion, 133
7.7 Confidence Interval for a Difference in Means, 136
7.8 Confidence Interval for a Difference in Proportions, 139
7.9 Recapping, 140
Appendix A: More on the Bootstrap, 141
Resampling Procedure–Parametric Bootstrap, 141
Formulas and the Parametric Bootstrap, 144
Appendix B: Alternative Populations, 144
Appendix C: Binomial Formula Procedure, 144
7.10 Exercises, 147
8 Hypothesis Tests 151
8.1 Review of Terminology, 151
8.2 A-B Tests: The Two Sample Comparison, 154
8.3 Comparing Two Means, 156
8.4 Comparing Two Proportions, 157
8.5 Formula-Based Alternative–t-Test for Means, 159
8.6 The Null and Alternative Hypotheses, 160
8.7 Paired Comparisons, 163
Appendix A: Confidence Intervals Versus Hypothesis Tests, 167
Confidence Interval, 168
Relationship Between the Hypothesis Test and the Confidence Interval, 169
Comment, 170
Appendix B: Formula-Based Variations of Two-Sample Tests, 170
Z-Test With Known Population Variance, 170
Pooled Versus Separate Variances, 171
Formula-Based Alternative: Z-Test for Proportions, 172
8.8 Exercises, 172
9 Hypothesis Testing–2 178
9.1 A Single Proportion, 178
9.2 A Single Mean, 180
9.3 More Than Two Categories or Samples, 181
9.4 Continuous Data, 187
9.5 Goodness-of-Fit, 187
Appendix: Normal Approximation; Hypothesis Test of a Single Proportion, 190
Confidence Interval for a Mean, 190
9.6 Exercises, 191
10 Correlation 193
10.1 Example: Delta Wire, 194
10.2 Example: Cotton Dust and Lung Disease, 195
10.3 The Vector Product and Sum Test, 196
10.4 Correlation Coefficient, 199
10.5 Other Forms of Association, 204
10.6 Correlation is not Causation, 205
10.7 Exercises, 206
11 Regression 209
11.1 Finding the Regression Line by Eye, 210
11.2 Finding the Regression Line by Minimizing Residuals, 212
11.3 Linear Relationships, 213
11.4 Inference for Regression, 217
11.5 Exercises, 221
12 Analysis of Variance–ANOVA 224
12.1 Comparing More Than Two Groups: ANOVA, 225
12.2 The Problem of Multiple Inference, 228
12.3 A Single Test, 229
12.4 Components of Variance, 230
12.5 Two-Way ANOVA, 240
12.6 Factorial Design, 246
12.7 Exercises, 248
13 Multiple Regression 251
13.1 Regression as Explanation, 252
13.2 Simple Linear Regression–Explore the Data First, 253
13.3 More Independent Variables, 257
13.4 Model Assessment and Inference, 261
13.5 Assumptions, 267
13.6 Interaction, Again, 270
13.7 Regression for Prediction, 272
13.8 Exercises, 277
Index 283