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Three high schools participated in a study to evaluate the effectiveness of a new computer. based mathematics curriculum. In each school, four 24 -student sections of freshman algebra were available for the study. The two types of instruction (standard curriculum, computer based curriculum) were randomly assigned to the four sections in each of the three schools. At the end of the term, a standard mathematics achievement test was given to each of the 24 students in each section. a. Is this study experimental, observational, or mixed experimental and observational? Why? b. Identify all factors, factor levels, and factor-level combinations. c. What type of study design is being implemented here? d. What is the basic unit of study?

A research laboratory was developing a new compound for the relief of severe cases of hay fever. The amounts of two active ingredients (low, medium, high) in the compound were varied at three levels each using 18 volunteers. Randomization was used in assigning volunteers to each of the treatment combinations. Data were collected on hours of relief. a. Is this study experimental, observational, or mixed? Why? b. Identify all factors. factor levels. and factor-level combinations. c. Describe how randomization would be performed in this study. d. What type of study design is being implemented here? e. What is the basic unit of study?