Chapter 9 Key Terms and Issues


KEY TERMS

External validity
Internal validity
Extraneous factors
History
Instrumentation
Matching
Maturation
Mortality
Pretest-posttest design
Regression
Selection
Selection by maturation interaction
Testing
Matching
Pretest-Posttest design


Key Issues


This chapter addresses four key questions:

1. What are Campbell and Stanley's threats to internal validity?
2. How do these threats operate in pretest/posttest designs?
3. How these threats operate in two-group designs?
4. What tradeoffs are commonly made between internal and external validity?


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