Fortuneâ€™s E-50 list. The Fortune E-50 is a listing of the top 50 electronic commerce and Internet-based companies, as determined by Fortune magazine each year. Fortune groups the companies into four categories: (1) ecompanies, (2) Internet software and service, (3) Internet hardware, and (4) Internet communication. Consider a study to compare the mean rates of return for the stock of companies in the four Fortune categories. Because the age of an electronic commerce or Internet-based company may have an impact on rate of return, the study is designed to remove any age variation. Four 1-year-old companies, four 3-year-old companies, and four 5-year-old companies were selected; within each age group, one company was randomly selected from category 1, one from category 2, one from category 3, and one from category 4.
a. What type of experimental design is employed?
b. Identify the key elements of the experiment (i.e., treatments, blocks, response variable, and experimental unit).