Upon completion of this chapter, the reader should be able to
 6.1  Illustrate each of the three primary criteria for establishing a causal relationship
 6.2  Describe the essential components of a true experimental research design
 6.3  Appraise the advantages and disadvantages of using quasi-experimental and
experimental designs
 6.4  Define five threats to validity in research
 6.5  Identify the most distinctive ethical challenges in experimental research