The Unit A Exam covers Chapters 11 - 13 in the book.
Review Key
33) Answers will vary. Possible answer: In an observational study, there is no manipulation of the variables and the researchers simply observe characteristics and take measurements. In an experiment, the researchers manipulate factor levels to create treatments, randomly assigning subjects to those treatment levels, and comparing the responses of the subject groups across treatment levels.
34) Answers will vary. Possible answer: The factors are the discrete variables whose levels are controlled by the experimenter. Experiments attempt to discover the effects that differences in factor levels may have on the responses of the experimental units. The treatments are the processes, interventions, or other controlled circumstances applied to randomly assigned experimental units. Treatments are the different levels of a single factor or are made up of combinations of levels of two or more factors.