Contents

Contents viiQUASI-EXPERIMENTS 321The Nonequivalent Control GroupDesign 322Nonequivalent Control Group Design:The Langer and Rodin Study 324Sources of Invalidity in the NonequivalentControl Group Design 327The Issue of External Validity 331Interrupted Time-Series Designs 332Time Series with Nonequivalent ControlGroup 335PROGRAM EVALUATION 336SUMMARY 340KEY CONCEPTS 342REVIEW QUESTIONS 342CHALLENGE QUESTIONS 343ANSWER TO STRETCHING EXERCISE 344ANSWER TO CHALLENGE QUESTION 1 344PART VAnalyzing and ReportingResearch 34511 Data Analysis and Interpretation:Part I. Describing Data,Confidence Intervals,Correlation 346OVERVIEW 347THE ANALYSIS STORY 348COMPUTER-ASSISTED DATA ANALYSIS 349ILLUSTRATION: DATA ANALYSIS FOR ANE XPERIMENT COMPARING MEANS 350Stage 1: Getting to Know the Data 350Stage 2: Summarizing the Data 355Stage 3: Using Confidence Intervals toConfirm What the Data Reveal 360ILLUSTRATION: DATA ANALYSIS FOR AC ORRELATIONAL STUDY 371Stage 1: Getting to Know the Data 372Stage 2: Summarizing the Data 372Stage 3: Constructing a ConfidenceInterval for a Correlation 377SUMMARY 377KEY CONCEPTS 379REVIEW QUESTIONS 379CHALLENGE QUESTIONS 380ANSWER TO STRETCHING EXERCISE 382ANSWER TO CHALLENGE QUESTION 1 38212 Data Analysis and Interpretation:Part II. Tests of StatisticalSignificance and the AnalysisStory 383OVERVIEW 384NULL HYPOTHESIS SIGNIFICANCE TESTING(NHST) 385EXPERIMENTAL SENSITIVITY AND STATISTICALPOWER 388NHST: COMPARING TWO MEANS 390Independent Groups 391Repeated Measures Designs 391STATISTICAL SIGNIFICANCE AND SCIENTIFICOR PRACTICAL SIGNIFICANCE 392RECOMMENDATIONS FOR COMPARING TWOMEANS 393REPORTING RESULTS WHEN COMPARING TWOMEANS 394DATA ANALYSIS INVOLVING MORE THAN TWOCONDITIONS 396ANOVA FOR SINGLE-FACTOR INDEPENDENTGROUPS DESIGN 396Calculating Effect Size for Designswith Three or More IndependentGroups 402Assessing Power for Independent GroupsDesigns 403Comparing Means in Multiple-GroupExperiments 404REPEATED MEASURES ANALYSIS OF VARIANCE 407TWO-FACTOR ANALYSIS OF VARIANCE FORI NDEPENDENT GROUPS DESIGNS 410Analysis of a Complex Design withan Interaction Effect 411Analysis with No Interaction Effect 413Effect Sizes for Two-Factor Designwith Independent Groups 414ROLE OF CONFIDENCE INTERVALS IN THE ANALYSISOF COMPLEX DESIGNS 414TWO-FACTOR ANALYSIS OF VARIANCE FOR AMIXED DESIGN 414