ABSTRACT
This chapter focuses on internal validity, which is the extent to which George A. Morgan and Jeffrey A. Gliner can infer that a relationship is causal. It discusses the causation and internal validity, which are dependent in good part on the type of approach and design. The chapter shows that the degree to which a study meets the material reinforcement, praise, and symbolic reinforcement condition for inferring causation is based on the strength of the design and internal validity. It presents discusses how internal validity is related to the issue of causation, and describe how to evaluate it. The chapter discusses the traditional threats to internal validity and how they fit into two main evaluative dimensions: the equivalence of the groups on participant characteristics, and control of extraneous experience and environmental variables. Control of extraneous experience/environment variables Equivalence of groups on participant characteristics internal validity.
