Select all of the true statements about a placebo-controlled randomized comparative experiment. A. The placebo control group is designed to control for bias on the part of the researcher. B. The experimental design of a placebo-controlled randomized comparative experiment involves dividing subjects into subgroups based on similar characteristics, followed by randomly assigning treatments to subjects within each subgroup. C. Experimental subjects are assigned to the treatment and control groups randomly, such that chance rather than conscious or unconscious decision determines which units end up receiving the treatment of interest and which receive the placebo. D. A placebo is an inactive substance that appears to be the same as the experimental treatment. The placebo effect is the phenomenon in which subjects report improvement in their condition after taking a placebo. E. A placebo control group receives the standard treatment or a diluted treatment. A placebo effect occurs when the placebo yields a positive response from subjects taking it.