Consider again the two-way ANOVA hypothesis test described in Problem 26. Recall that the relevant data are given in the file P12_26.XLS.

a. A natural gas supplier claims that homes that use gas heat generate an average February heating bill that is Jess than the average February heating bill of all other homes that use electricity or heating oil. Is this claim supported by the given data? Explain.

b. A heating oil supplier claims that homes that use heating oil generate an average February heating bill that is less than the average February heating bill of all other homes that use electricity or natural gas. Is this claim supported by the given data? Explain.

Problem 26

A study is performed on a sample of residential homes to discover whether the size of the monthly heating bill depends on the type of heat or the type of home. In particular, three types of heat are examined: electric, natural gas, and oil. Also, all homes are classified into two types: those on a single level and those with at least two stories. In a single community, ten houses of each type, using each type of heat, are located and their heating bills for February of the past year are observed. These data are recorded in the file P12_26.XLS. Assume that the homes in this study are approximately equivalent in terms of overall square footage and level of insulation.