Dr. Sullivan is conducting a clinical trial to determine if vitamin Z can improve test performance of students in an introductory college nutrition course. Dr. Sullivan puts all the students' names in a hat and draws names to determine if they will be placed in the control or the experimental group. The experimental group receives a capsule of vitamin Z and the control group a "sugar pill" that tastes and looks identical to the vitamin Z capsule. Neither Dr. Sullivan nor the participants knows who is receiving which treatment. This experiment is BEST described as_________________.

Relating to, or is an experimental treatment in which, during most of the honors course of the experiments neither the participants nor the experimenters recognize whose variables are in the research and control classes.
Random selection relates to how the group is taken from the overall population, while the representative sample applies to how the samples are then allocated either to the trial or control groups.
Placebo-controlled studies are a way to check a medical therapy during which a rotary knob sample, in addition to a community of patients undergoing the care to be tested, experiences a simulated "placebo" medication that is designed specifically to have no actual effect.