Question

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As part of a study designed to compare hybrid and similarly equipped conventional vehicles, Consumer Reports tested a variety of classes of hybrid and all-gas model cars and sport utility vehicles (SUVs). The following data show the miles-per-gallon rating Consumer Reports obtained for two hybrid small cars, two hybrid midsize cars, two hybrid small SUVs, and two hybrid midsize SUVs; also shown are the miles per gallon obtained for eight similarly equipped conventional models.

Make/Model	Class	Type	MPG
Honda Civic	Small Car	Hybrid	37
Honda Civic	Small Car	Conventional	28
Toyota Prius	Small Car	Hybrid	44
Toyota Corolla	Small Car	Conventional	32
Chevrolet Malibu	Midsize Car	Hybrid	27
Chevrolet Malibu	Midsize Car	Conventional	23
Nissan Altima	Midsize Car	Hybrid	32
Nissan Altima	Midsize Car	Conventional	25
Ford Escape	Small SUV	Hybrid	27
Ford Escape	Small SUV	Conventional	21
Saturn Vue	Small SUV	Hybrid	28
Saturn Vue	Small SUV	Conventional	22
Lexus RX	Midsize SUV	Hybrid	23
Lexus RX	Midsize SUV	Conventional	19
Toyota Highlander	Midsize SUV	Hybrid	24
Toyota Highlander	Midsize SUV	Conventional	18

At the α = 0.05 level of significance, test for significant effects due to class, type, and interaction.

Find the value of the test statistic for class. (Round your answer to two decimal places.)

Find the p-value for class. (Round your answer to three decimal places.)

p-value =

State your conclusion about class.

Because the p-value ≤ α = 0.05, class is not significant.Because the p-value > α = 0.05, class is not significant.    Because the p-value ≤ α = 0.05, class is significant.Because the p-value > α = 0.05, class is significant.

Find the value of the test statistic for type. (Round your answer to two decimal places.)

Find the p-value for type. (Round your answer to three decimal places.)

p-value =

State your conclusion about type.

Because the p-value ≤ α = 0.05, type is not significant.Because the p-value > α = 0.05, type is significant.    Because the p-value > α = 0.05, type is not significant.Because the p-value ≤ α = 0.05, type is significant.

Find the value of the test statistic for interaction between class and type. (Round your answer to two decimal places.)

Find the p-value for interaction between class and type. (Round your answer to three decimal places.)

p-value =

State your conclusion about interaction between class and type.

Because the p-value ≤ α = 0.05, interaction between class and type is significant.Because the p-value > α = 0.05, interaction between class and type is significant.    Because the p-value ≤ α = 0.05, interaction between class and type is not significant.Because the p-value > α = 0.05, interaction between class and type is not significant.

Answer 1

Minitab output:

Two-way ANOVA: MPG versus Type, Class

Source DF SS MS F P
Type 1 182.25 182.250 29.76 0.001
Class 3 441.25 147.083 24.01 0.000
Interaction 3 19.25 6.417 1.05 0.423
Error 8 49.00 6.125
Total 15 691.75

The value of the test statistic for class=24.01

p-value =0.000

Because the p-value ≤ α = 0.05, class is significant.

The value of the test statistic for type=29.76  

p-value =0.001

Because the p-value ≤ α = 0.05, type is significant.

The value of the test statistic for interaction between class and type=1.05

p-value =0.423

Because the p-value > α = 0.05, interaction between class and type is not significant.