A controlled experiment___. A. Includes one group for which the scientist controls all variables. B. Includes at least two group
s, one of which does not receive the experimental treatment. C. Includes at least two groups, one differing from the other by two or more variables. D. Is repeated many times to ensure that the results are accurate.
Includes at least two groups, one of which does not receive the experimental treatment. (B)
Explanation:
A controlled experiment is made up of at least two groups of participants (subjects). One group (the test group) receives the experimental treatment, which can be an intervention or a new drug to be tested etc, and the effect of the treatment on the subjects is measured, while the second group of similar subjects also known as the control group acts as a baseline and do not receive the treatment or intervention. They act as a baseline to ensure that the change observed in the treatment group was brought about as a result of the treatment.
<em>Note that repeating the experiment several times does not ensure accuracy of the result, rather it ensures reliability of the results hence option D is not correct</em>
