In order to assess the effectiveness of a new fertilizer, researchers applied the fertilizer to the tomato plants on the west side of a garden but did not fertilize the plants on the east side of the garden. They later measured the weights of the tomatoes produced by each plant and found that the fertilized plants grew larger tomatoes than did the non fertilized plants. They concluded that the fertilizer works.
(a) Was this an experiment or an observational study? Why?
(b) This study is seriously flawed. Use the language of statistics to explain the flaw and how this affects the validity of the conclusion reached by the researchers.
(c) Could this study have used the concept of blinding (i.e., does the word "blind" apply to this study)? If so. how? Could it have been double-blind? If so, how?