Corrosion prevention of buried steel structures. Refer to the Materials Performance (Mar. 2013) study to compare two tests for steel corrosion of underground piping, LO4 Exercise 1.17 (p. 48). The two tests, which engineers call

“instant-off” and “instant-on” potential, were applied to buried piping at a petrochemical plant in Turkey. Recall that both the “instant-off” and “instant-on” tests were used to make predictions of corrosion at each of 19 different randomly selected pipe locations. The researchers want to compare the mean accuracy of the corrosion predictions for the two tests in order to determine if one test is more desirable than the other when applied to buried steel piping.

a. What are the experimental units for this study?

b. What type of design is employed? Identify the features (e.g., treatments, blocks) of the design.

c. What is the dependent (response) variable of interest?

d. Illustrate the layout of this design using a graphic similar to Figure 10.21.

e. State H0 and Ha in symbols.