Question

A team of researchers conduct an experiment to see whether adding the compound Fioretin (FRT) to soil will cause orchids to bloom longer. They take orchids of the genus Cattleya (Cats) and assign half of them to a group that receive FRT and half of them to a group that does not receive FRT. They repeat this process with orchids of the genus Phalaenopsis (Pals). All the orchids are grown under the same conditions inside the same greenhouse.

a. What is the control group in this experiment?

b. Is this a blocked experiment? If so, what is the blocking variable?

c. How would you make this a single-blind experiment?

Answer 1

a) The control group is the group that does not receive FRT and is used to measure the results of the other group if there is any relative change or not.

b) This is a blocked experiment as two different types of genus are used. The blocking variable is genus of orchids (Cattleya and Phalaenopsis)

c) The experiment is a single blind experiment when the participants are not aware about the treatment they are receiving to prevent any bias. In this case, the participants are orchids and hence it is not required. The experiment can become a double blind experiment if we give both the groups a coded compound (one which contains FRT and one which does not contain anything). This would prevent bias in the researchers.