ABSTRACT
In surveys, researchers are “passive” gatherers of information about behaviors, attitudes, and beliefs. In other words, they attempt to measure what exists at a given point in time without trying to change or modify the respondents. Some experiments have two groups of subjects: one group that is introduced to the cause or “stimulus” by the researcher and then observed for an effect, and a second group that is not exposed to the cause but is observed. In the randomized experiment, the subjects are assigned to each group by a procedure that gives each recruited subject an equal chance of being in either the experimental or control group. For example, a coin toss for each subject will result in either a “heads” or “tails.” Random assignment ensures that both groups are reasonably similar at the beginning of the experiment, since each individual could have been assigned to either group by the random procedure.
