Contents

viContentsTHE ROLE OF PRACTICE EFFECTS IN REPEATEDMEASURES DESIGNS 228Defining Practice Effects 229Balancing Practice Effects in the CompleteDesign 230Balancing Practice Effects in theIncomplete Design 235DATA ANALYSIS OF REPEATED MEASURESDESIGNS 240Describing the Results 240Confirming What the ResultsReveal 241THE PROBLEM OF DIFFERENTIAL TRANSFER 243SUMMARY 244KEY CONCEPTS 246REVIEW QUESTIONS 246CHALLENGE QUESTIONS 246ANSWER TO STRETCHING EXERCISE 247ANSWER TO CHALLENGE QUESTION 1 2488 Complex Designs 249OVERVIEW 250DESCRIBING EFFECTS IN A COMPLEXDESIGN 250An Example of a 2 2 Design 251Main Effects and InteractionEffects 253Describing Interaction Effects 257Complex Designs with ThreeIndependent Variables 260ANALYSIS OF COMPLEX DESIGNS 261Analysis Plan with an InteractionEffect 263Analysis Plan with No InteractionEffect 266INTERPRETING INTERACTION EFFECTS 268Interaction Effects and TheoryTesting 268Interaction Effects and ExternalValidity 269Interaction Effects and Ceiling and FloorEffects 271Interaction Effects and the NaturalGroups Design 272SUMMARY 275KEY CONCEPTS 276REVIEW QUESTIONS 276CHALLENGE QUESTIONS 277ANSWER TO STRETCHING EXERCISE I 277ANSWER TO STRETCHING EXERCISE II 278ANSWER TO CHALLENGE QUESTION 1 278PART IVApplied Research 2799 Single-Case Designs and Small-nResearch 280OVERVIEW 281THE CASE STUDY METHOD 282Characteristics 282Advantages of the Case Study Method 285Disadvantages of the Case StudyMethod 288Thinking Critically About TestimonialsBased on a Case Study 290SINGLE-SUBJECT (SMALL-n) EXPERIMENTALDESIGNS 291Characteristics of Single-SubjectExperiments 294Specific Experimental Designs 295Problems and Limitations Common to AllSingle-Subject Designs 303SUMMARY 305KEY CONCEPTS 306REVIEW QUESTIONS 306CHALLENGE QUESTIONS 307ANSWER TO STRETCHING EXERCISE 308ANSWER TO CHALLENGE QUESTION 1 30810 Quasi-Experimental Designsand Program Evaluation 309OVERVIEW 310TRUE EXPERIMENTS 311Characteristics of True Experiments 311Obstacles to Conducting TrueExperiments in Natural Settings 311Threats to Internal Validity Controlled byTrue Experiments 314Problems That Even True ExperimentsMay Not Control 318