Final answer:
Experimental studies involve applying a treatment to subjects and comparing them to a control group, while observational studies involve observing and measuring characteristics without manipulating variables.
Step-by-step explanation:
Experimental studies and observational studies differ in how subjects are treated. In an experimental study, the researcher applies a treatment to a group of subjects and compares it to a control group to isolate the effects of the treatment.
For example, Jonas Salk conducted an experimental trial of the polio vaccine by giving it to a group of children and comparing them to a control group. On the other hand, in an observational study, no attempt is made to influence the subjects. The researcher simply observes and measures characteristics in a sample without manipulating variables.
For example, a political poll is an observational study that measures opinions of potential voters. Both types of studies provide valuable insights in science, but only experimental studies can rigorously test cause-and-effect hypotheses under controlled conditions. However, the ethical implications of experimental design are important to consider, as not all experiments are feasible or ethical to conduct.