Answer
a. This is an example of designed experiment. Because the patients are selected at random and they were being randomly assigned to different groups. The conclusion is invalid because the physicians had access to the information regarding which patients belong to treatment or control groups.
b. This is a designed experiment because the experimenter controls the assignment of elements to different treatment groups at random.
c. This is not a double blind study because the physicians had access to the information regarding which patients belong to treatment or control groups.
Work Step by Step
a. This is an example of designed experiment. Because the patients are selected at random and they were being randomly assigned to different groups. The conclusion is invalid because the physicians had access to the information regarding which patients belong to treatment or control groups.
b. This is a designed experiment because the experimenter controls the assignment of elements to different treatment groups at random.
c. This is not a double blind study because the physicians had access to the information regarding which patients belong to treatment or control groups.