The essential difference between an experiment and an observational study is that
A) observational studies always involve large numbers of subjects, but experiments never do.
B) in an experiment, information is gathered only on animals or things, but in an observational study, only information about people is gathered.
C) an observational study imposes treatments on the subjects, but an experiment does not.
D) observational studies cannot have variables.
E) an experiment imposes treatments on the subjects, but an observational study does not.

Question

Quizplus · Accepted Answer

The essential difference between an experiment and an observational study is that an experiment imposes treatments on the subjects, while an observational study does not. In an observational study, the researcher observes and records data without intervening or imposing treatments. In contrast, an experiment involves manipulating a variable of interest to observe the effect on an outcome, which necessitates imposing treatments on the subjects. The other options are incorrect: A is not true, B is overly limiting and incorrect, C is incorrect as both studies can impose treatments, and D is incorrect as both studies involve variables.

The Essential Difference Between an Experiment and an Observational Study