Refer to Exercise 34 on
emissions.
(a) Is it sensible to ask which utility produces the largest level of
emissions? If so, identify the plant with the greatest increase and determine whether it is statistically significantly higher than that of the other utilities.
(b) Repeat (a) but for the effects of fuel type.
Exercise 34
Pollution The data in this exercise describe the amount of
produced in generating electricity (measured in grams of
per kilowatt-hour of electricity generated). Results are from several measurements taken during a year at several plants run by four different electricity-generating utilities using each of three types of fuel: natural gas, coal, and fuel oil.4
(a) These data are not from a randomized experiment. What are the implications for modeling the data as a two-way ANOVA?
(b) The measurements were made at different times during the year. What assumption about the twoway ANOVA model becomes questionable as a result?
(c) Are these data balanced? Why or why not?
(d) What does the profile plot indicate? Explain your choice of the variable for the
-axis of the plot.
(e) Perform the two-way ANOVA. What conclusions are implied by the ANOVA summary table, particularly in light of the discovery of major natural gas reserves in the United States?