In each of the following scenarios, deine the type of measurement scale.
a. An investor collects data on the weekly closing price of gold throughout a year.
b. An analyst assigns a sample of bond issues to one of the following credit ratings, given in descending order of credit quality (increasing probability of default): AAA, AA, BBB, BB, CC, D.
c. The dean of the business school at a local university categorizes students by major (i.e., accounting, finance, marketing, etc.) to help in determining class offerings in the future.