Question

An environmentalist would like to compare the mean number of miles per gallon (mpg) obtained by filling up with e85 versus regular unleaded gasoline. To do so, he selects a random sample of 100 vehicle owners and asks them to report their fuel economy (in mpg) for their next fill-up. He notices that some of the participants drive compact cars, some drive mid-sized cars, some drive trucks, and some drive SUVs. The researcher wants to use a matched pairs design. In order to isolate the effect of fuel type on fuel economy, what should the researcher use as pairs?

1) Vehicles of similar sizes
2) Vehicles that are the same color
3) Vehicles that are assigned to receive the same type of fuel
4) Vehicles that are driven more often versus less often

Answer 1

Step-by-step explanation:

Answer 2

The matched pairs design for comparing e85 versus regular unleaded fuel economies should pair vehicles of similar sizes to control for variables such as weight and engine size.

Step-by-step explanation:

The environmentalist should use vehicles of similar sizes as pairs to isolate the effect of fuel type on fuel economy. This approach allows comparison within the same vehicle category, controlling for variables such as weight and engine size that could affect MPG. To implement the matched pairs design, each vehicle owner could fill up once with e85 and once with regular unleaded, recording the MPG for each type of fuel. The pairs of MPG figures would then be compared to see if there is a statistically significant difference between the fuels.

For example, one might pair a compact car that uses e85 with the same model of compact car that uses regular unleaded, ensuring a consistent basis for comparison. MPG can be greatly influenced by car size, and this method allows the researcher to focus on the impact of the fuel itself, rather than the type of vehicle. This design is the most effective in establishing the relationship between fuel type and fuel economy across different vehicle sizes.