Final answer:
The independent variable is the factor that the experimenter controls or manipulates in an experimental study, and it is the only significant difference between the experimental and control groups, with its effects observed in the dependent variable.
Step-by-step explanation:
The independent variable is influenced or controlled by the experimenter; in a sound experimental study, this variable is the only important difference between the experimental and control group. An experimental study involves manipulating the independent variable to determine its effect on the dependent variable, which is the outcome being measured. For instance, if a researcher is studying the effect of a certain drug on patient recovery time, the presence or amount of the drug is the independent variable while the recovery time is the dependent variable.
In ideal experimental design, the experimental group receives the manipulation of the independent variable, and the control group does not, ensuring that any observed difference in the dependent variable can be attributed to the experimental treatment and not other factors. Researchers carefully conduct statistical analysis to confirm whether the differences observed are significant and not due to chance, hence supporting or refuting the hypothesis posed.