oIndependent variable (experimental stimulus), dependent variable – what are these? When are they measured?oPretest and posttest – What happens during these phases?oExperiment and control group – How do they differ? How are they the same?-What is a placebo? Which group receives the placebo?-Describe the key components of a Solomon 4-Group design, as well as a Posttest-Only Control Group design.-What is a major methodological advantage of the Solomon 4-Group design?Validity Issues-In experimental design, what is internal validity? Why are threats to internal validity important? What does it mean to say that study effects are confounded? How were the results of the Pepsi Challenge confounded? Discuss the Pepsi Challenge and the threat to internal validity in the Pepsi Challenge.-Describe how each of the following can affect internal validity:oSelection bias, history/historical events, (repeated) testing, experimental mortality,contamination/diffusion of treatment, experimenter expectancy/bias, maturation, instrumentation, and statistical regression to the mean.
- Spring '19
- internal validity, natural experiments