Question

4. Cara is bored at home and decides to do a gardening experiment. She has 8 tomato starts and wants to give half of them an organic fertilizer and half of them no fertilizer. She gives each plant a number and randomly assigns it to the control or treatment group and plants it in a randomized space in the garden. (6 points) a. Describe the control group and why it is necessary in an experiment. b. Why were the subjects randomly assigned to the groups and spaces in the garden?

Answer 1

$\textbf{a.}$

A control group is a statistically significant portion of participants in an experiment that are shielded from exposure to variables. Thus the control group here is the half of the tomatoes which do not receive any fertilizer.

A control group is necessary in an experiment. An experiment is the study to gather information on the effect of an external treatment or variable. The treatment is applied to the case group, and then the difference between the case group and the control group is observed. Without a control group, there will be no way to compare the effects of a treatment to the effects of no treatment. Here in this case, the twogroups are the half of the tomatoes on which the fertilizer is applied, and the half of the tomatoes which do not receive any fertilizer. The effect of the fertilizer can be understood best by observing the difference between the two groups. As all the two groups are similar in terms of all other factors, the change in the half of the tomatoes on which the fertilizer is applied can be credited solely to the fertilizer.

$\textbf{b.}$

Random assignment of the subjects to the groups and space in the garden is to try to eliminate bias as much as possible. Cara must be fair and not choose any tomato over the others for some personal preference.