Preface 

VII  

How to Make a Decision with Statistics 


1  (58) 

IntroductionStatistics and the Scientific Method 


1  (1) 


2  (1) 

The Language of Statistical Decision Making 


3  (9) 


4  (2) 

How Do We Decide Which Theory to Support? 


6  (3) 

What Errors Could We Make? 


9  (3) 


12  (24) 


14  (6) 

More on the Direction of Extreme 


20  (3) 

How Unusual Are the Data?: The pvalue 


23  (13) 

Significant versus Important 


36  (23) 


39  (1) 


40  (1) 


40, 55  (46) 

Appendix 1.A Selecting Two Vouchers 


46  (5) 

1.A.1 Forming a Decision Rule 


51  (3) 

1.A.2 What's in the Bag? pvalue When the Sample Size is 2 


54  (5) 


59  (46) 


59  (1) 


60  (1) 


60  (3) 


63  (5) 


68  (7) 

Stratified Random Sampling 


75  (6) 


81  (4) 


85  (4) 


89  (16) 


94  (1) 


95  (1) 


95  (7) 


102  (3) 

Observational Studies and Experiments 


105  (42) 


105  (1) 


105  (1) 


106  (7) 

Observation versus Experimentation 


106  (1) 


107  (3) 

A Problem Called Confounding 


110  (3) 

Understanding Observational Studies 


113  (5) 

Types of Observational Studies 


113  (3) 

Difficulties in Observational Studies 


116  (2) 

Understanding Experiments 


118  (12) 


118  (4) 

Principles for Planning an Experiment 


122  (8) 

Reading with a Critical Eye 


130  (4) 


134  (13) 


137  (1) 


138  (1) 


138  (9) 

Summarizing Data Graphically 


147  (46) 


147  (1) 


148  (9) 


149  (3) 


152  (3) 

Distribution of a Variable 


155  (2) 

Displaying DistributionsQualitative Variables 


157  (6) 


157  (1) 


158  (5) 

Displaying DistributionsQuantitative Variables 


163  (18) 


163  (3) 


166  (6) 


172  (6) 


178  (3) 

Guidelines for Plots, Graphs, and Pictures 


181  (12) 


184  (1) 


185  (1) 


185  (4) 


189  (4) 

Summarizing Data Numerically 


193  (42) 


193  (1) 


194  (9) 

Measuring Variation or Spread 


203  (17) 

Linear Transformations and Standardization 


220  (15) 


225  (1) 


226  (1) 


226  (6) 


232  (3) 

Using Models to Make Decisions 


235  (42) 


235  (1) 

Why Do We Need to Know Models? 


236  (1) 

Modeling Continuous Variables 


237  (20) 


238  (15) 


253  (4) 

Modeling Discrete Variables 


257  (20) 


262  (1) 


263  (1) 


263  (5) 


268  (9) 


277  (72) 


277  (1) 

Two Quantitative Variables 


278  (44) 


279  (4) 


283  (3) 

Calculating the Least Squares Regression Line 


286  (6) 

Statistically Significant Relationship? 


292  (6) 


298  (3) 

Influential Points and Outliers 


301  (4) 

Correlation: How Strong Is the Linear Relationship? 


305  (11) 


316  (6) 

When Scatterplots Don't Work: Two Qualitative Variables 


322  (27) 

Marginal and Conditional Distributions 


322  (4) 

Is There a Significant Relationship? 


326  (2) 


328  (5) 


333  (1) 


333  (1) 


333  (12) 


345  (4) 

How to Measure Uncertainty with Probability 


349  (66) 


349  (1) 


350  (1) 


351  (7) 

The Language of Probability 


358  (25) 


359  (6) 


365  (10) 

Partitioning and Bayes's Rule 


375  (8) 


383  (32) 

Discrete Random Variables 


384  (6) 

Continuous Random Variables 


390  (5) 


395  (1) 


396  (1) 


397, 411  (403) 

Appendix 8.A The Binomial Distribution 


403  (10) 


413  (2) 

Sampling Distributions: Measuring the Accuracy of Sample Results 


415  (40) 


415  (1) 

Sampling Distribution of a Sample Proportion 


416  (6) 


422  (16) 

Sampling Distribution of a Sample Mean 


438  (17) 


445  (2) 


447  (1) 


447  (4) 


451  (4) 

Making Decisions with Confidence 


455  (72) 


455  (1) 

Making Decisions about a Population Proportion 


456  (14) 

Making Decisions about a Population Mean 


470  (18) 

Known Population Standard Deviation 


471  (5) 

Unknown Population Variance 


476  (12) 

Confidence Interval Estimation: For a Proportion 


488  (11) 

Confidence Interval Estimation: For a Mean 


499  (8) 

Confidence Intervals and Hypothesis Testing 


507  (20) 


509  (1) 


510  (1) 


511  (8) 


519  (8) 


527  (50) 


527  (2) 

Paired Samples versus Independent Samples 


529  (5) 


534  (9) 

Independent Samples: Comparing Means 


543  (16) 

Independent Samples: Comparing Proportions 


559  (18) 


566  (1) 


567  (1) 


567  (5) 


572  (5) 

Comparing Many Treatments 


577  (36) 


577  (3) 


580  (5) 

The FTest Statistic and the Fdistribution 


585  (5) 

ANOVA: Letting the Computer Do the Work! 


590  (3) 

How Do We Get the Mean Squares? 


593  (7) 

What Does Reject H0 in Anova Mean? (And What Doesn't It Mean?) 


600  (13) 


605  (1) 


606  (1) 


606  (3) 


609  (4) 


613  (40) 


613  (1) 


614  (3) 


617  (8) 


625  (9) 


634  (19) 


641  (1) 


642  (1) 


642  (7) 


649  (4) 
Appendix 

653  (10) 
Answers to OddNumbered Exercises 

663  (11) 
Index 

674  