A controlled experiment is one in which
A) the experiment is repeated many times to ensure that the results are accurate.
B) the experiment proceeds at a slow pace to guarantee that the scientist can carefully observe all reactions and process all experimental data.
C) there are at least two groups, one of which does not receive the experimental treatment.
D) there are at least two groups, one differing from the other by two or more variables.
E) there is one group for which the scientist controls all variables.

Question

Quizplus · Accepted Answer

A controlled experiment involves at least two groups, one of which serves as the control group that does not receive the experimental treatment. This allows the scientist to compare the results of the group that received the treatment to those that did not, determining if the treatment had an effect. Option A is incorrect because repeatability and accuracy do not depend on how fast or slow the experiment proceeds. Option B is incorrect because the pace of the experiment does not ensure careful observation or data processing, but rather the scientist's skills and attention to detail ensure these factors. Option D is incorrect because the groups should only differ by one variable, which is the experimental treatment. Option E is incorrect because there can be multiple variables that are controlled by the scientist, but the experimental group must differ in only one variable.

A Controlled Experiment Is One in Which