Use the following description to answer the next five (5) questions: Suppose tha

Question

Use the following description to answer the next five (5) questions: Suppose that an engineer wants to know whether a gasoline additive increases fuel efficiency (miles per gallon). The study used a single car (to eliminate car-to-car variability) and a sequence of trials in which 1 gallion of gas is put in an empty tank, the car is driven around a racetrack at a constant speed, and the distance traveled on the gallon of gas is recorded. To determine whether the additive increases gas mileage, it would be necessary to include a control group of trials where distance traveled was measured when gasoline without the additive was used. The car trials would be assigned at random to one of the two conditions (additive or no additive). 9. The study is an: A. experiment. B. observational study. 10. What is an individual in the study? A. Car B. Car trial C. Driver D. Gasoline 11. What is the response variable? A. B. C. D. Car-to-car variability Car trial Fuel efficiency Gasoline additive (Yes, No) 12. What is the explanatory variable? A. Car-to-car variability B. Car trial C. Fuel efficiency D. Gasoline additive (Yes, No) 13. Even though the study consists of a sequence of trials all with the same car, random assignment of trials to one of the two conditions (additive or no additive) is still important because there is always a possibility of extraneous variables. Possible extraneous variables are: A. Air temperature B. Other environmental conditions C. Physical condition of the car D. All of the above. 14. If one is interested in generalizing the results of a sample to a population, then which one is most important? Random sampling from the population Random assignment of treatments to units A. B. 15. If one wishes to establish causation (ie, the explanatory variable causes changes in the response variablel. then which one is most important? A. Random sampling from the population B. Random assignment of treatments to units

Explanation / Answer

9) Explanatory Variable

10) The individual in the study is CAR

11) Response Variable or Dependent variable is Fuel Efficiency

12) Explanatory Variable or Independent Variable is Gasoline additive (Yes,No)

13) Extraneous variables : Air temperature, Physical condition of the car and other environmental conditions.

14) Random sampling from population.

15) Random assignments of treatments to units.

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