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.

Question

Quizplus · Accepted Answer

A controlled experiment involves manipulating one variable and keeping all other variables constant. In order to properly determine the effect of the manipulated variable, there must be at least two groups - one that is subject to the experimental treatment and one that is not (the control group). This allows for comparison and determination of causality. Option A refers to replication, which is important in scientific research but is not specific to controlled experiments. Option B refers to observation and data processing, which are important but are not specific to controlled experiments. Option D refers to the manipulation of multiple variables, which can make it difficult to determine causality and is not specific to controlled experiments.

A Controlled Experiment Is One in Which