Final answer:
An observational study does not involve manipulation of variables, while an experiment involves manipulating an independent variable to observe its effect on a dependent variable. The experimental group is exposed to this manipulation and compared with a control group to determine the influence of the variable.
Step-by-step explanation:
During an observational study, the experimenter/therapist would not manipulate any variables, whereas during an experiment, the experimenter/therapist would manipulate variables. In an observational study, the goal is to monitor and record data without intervention. In contrast, experiments involve the deliberate manipulation of an independent variable to study its effect on a dependent variable. The experimenter creates two groups: the experimental group and the control group. The experimental group is exposed to the independent variable, while the control group is not. This design allows the researcher to observe the effects of the manipulation and control for other variables that might influence the outcome. Therefore, if the experiment is conducted properly and shows a significant difference in the dependent variable between the groups, it suggests that the independent variable has had an impact.