Edgar is a psychologist interested in the effects of the presence of self-checkout counters on customer satisfaction. He convinces a large clothing company to consider adding self-checkout counters to some of its stores. Edgar's hypothesis is that if self-checkout counters are introduced, customers will be more satisfied. He is proposing an experimental study to examine this belief.

Required:
a. Identify the dependent variable in the study.
b. Identify the experimental group in this study.
c. Provide an example of a valid operational definition of "customer satisfaction."
d. Explain how random assignment would help establish cause and effect in this experiment.