Final answer:
The main difference between an observational study and an experiment is that in an experiment, the researchers control treatment and analyze cause-and-effect relationships, while in an observational study, they do not control treatment and do not directly analyze cause-and-effect relationships.
Step-by-step explanation:
In an observational study, the researchers do not control treatment, and in an experiment, they do control treatment. This means that in an observational study, the researcher simply observes and measures naturally occurring variables, while in an experiment, the researcher manipulates an independent variable to observe its effect on a dependent variable.
Moreover, in an experiment, cause-and-effect relationships are analyzed, whereas in an observational study, cause-and-effect relationships are not directly analyzed. Experimental studies are considered the gold standard in scientific research because they allow for stronger conclusions about cause and effect.
For example, an observational study might find a correlation between smoking and lung cancer, but it cannot determine whether smoking directly causes lung cancer. In contrast, an experiment could manipulate smoking levels and directly observe the effect on lung cancer rates, allowing for stronger conclusions about causation.