Question

Diane wanted to demonstrate which pruning technique was best for controlling the growth of certain types of shrubs. She selected ten shrubs of the same type and randomly assigned each one to receive one of ten different pruning methods. Two weeks after pruning, she measured the regrowth, in inches, of the shrubs; the pruning method that minimized regrowth was recommended as the best method. Which of the following best describes why this is not a well-designed experiment?
A. The shrubs were not randomly selected.
B. Pruning methods were not randomly assigned to shrubs.
C. Each pruning method was used on only one shrub.
D. Each shrub did not receive all ten pruning methods.
E. Only two treatments should be used in an experiment.

Answer 1

Answer:

C. Each pruning method was used on only one shrub.

Explanation:

Reproducibility is one of the most important factors contributing to the reliability of scientific research. The researcher must be able to achieve the same results two to three times. In biological research, this is usually done in the from of triplicates i.e. one experiment is repeated three times. This is done for two reasons:

1. Producing reproducible results
2. Ruling out false positives (a negative result that presents as positive due to error) and negatives (a positive result that presents as negative due to error)

Triplicates rule out the possibility that the observed change was caused by another factor or through mere chance. Therefore, in the current scenario, each pruning method should have been applied to multiple (at least 3) samples of a shrub.