Additional Principles of Experimental Design — Quiz
Question 6 • Statistics and Probability
A farmer learns of a new type of corn that is supposed to have a higher yield of ears. From previous crops, he knows approximately how many ears of corn 10 plants will produce from the original seeds. The farmer decides to plant the new type of corn to determine if the seeds will produce a higher number of ears of corn. He plants the first 100 seeds of the new type of corn seeds in the field he uses for corn. When it is time to harvest, he randomly selects 10 plants and counts the number of ears. The farmer compares the number of ears with the yield he received the previous year from 10 plants using the original corn seeds. Because the new type of corn produced a higher number of ears, he concludes that the new type of corn does produce more ears of corn. Which of the following statements is not true about this experimental design?
Answer
A
Because the farmer did not have two groups growing at the same time, one with the new type of corn and one with the original type of corn, the conclusion may be suspect.
B
Because the farmer used the seeds from the top of the packet and did not randomly select the seeds, the conclusion is suspect.
C
There may be other variables that affected the yield of corn between this year’s crop and last year’s crop; therefore, the conclusion would be suspect.
D
Because the farmer used a comparison between the yield of the new type of corn and the yield from the previous corn seeds, the conclusion is valid.
Explanation
The conclusion is not necessarily valid just because the farmer compared this year’s new corn with last year’s original corn. Growing the two types in different years leaves other factors—such as weather or soil conditions—that could explain the difference in yield. Therefore, statement D is not true: the comparison alone does not prove the new seeds produce more ears.
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