A consumer research company is interested in determining if a certain company's new refrigerator model is more efficient than the older model. Researchers decide to investigate the claim that the new model uses 10% less electricity than the older model for the same cooling load. To collect data, the company obtains 20 random refrigerators for each model. They are all placed in one building well separated from each other and are loaded with 50 bottles of water. The electricity usage is monitored for one month. How can the results be generalized?
A. The conclusions should be applicable to any unit of the new model as compared to any unit of the old model.
B. The conclusions should be applicable to all refrigerators made by the same manufacturer.
C. The conclusions only apply to the sample that was obtained for the new models as compared to the sample that was obtained for the old model.
D. The conclusions should be valid for new model refrigerators from