Final answer:
The independent variable is the one manipulated by the researcher to study its effects on the dependent variable in an experiment.
Step-by-step explanation:
The independent variable is the experimental factor that is manipulated; the variable whose effect is being studied. In a scientific experiment, this is the variable that the researcher changes or controls to investigate its effect on another variable, which is known as the dependent variable. The independent variable is critical in testing hypotheses and is often contrasted with the dependent variable, which is the outcome variable that researchers measure to see the effects of the manipulation. It is essential to control any other variables, known as control variables, to ensure that the observed effects are solely due to the changes in the independent variable.