When both the researchers and the participants do not know who is in the experimental group and do not know who is in the control group, this type of study is known as
A. placebo controlled.
B. quasi-experimental.
C. unwise.
D. double blind.
Answer:D
When both the researchers and the participants do not know who is in the experimental group and do not know who is in the control group, this type of study is known as
A. placebo controlled. B. quasi-experimental. C. unwise. D. double blind.