Question:

Volunteers were asked to be a part of an experiment to test the effectiveness of a vaccine on combating a virus. From the pool of volunteers, 80 are selected at random to participate. Researchers randomized the participants into two groups of equal size. The rst group received a placebo injection of the vaccine (placebo means they received no active treatment). The second group received an injection of the vaccine. Both the researchers and participants were unaware of whether the received the placebo or the My; vaccine. After a period, researchers tested participants for presence of virus antibodies. According to the CDC, Antibodies are proteins that help ght off infections and can provide protection against getting that disease again (immunity). Antibodies are disease specic. 1. The populations in this experiment are A. Dependent or paired B. Independent 2. This experiment follows which design: A. Completely random experiment B. Completely randomized block experiment C. matched pairs randomized design 3. The response in this experiment is the A. injection of vaccine or m B. presence of antibodies 4. This experiment is dnuhlszlinded meaning the researchers and the participants are unaware of which treatment they receive. Why is this an important feature of an experiment? A. Reduced the presence of confounding variables B. Keep the results random C. Reduce inherent bias