What Is the Difference Between the Dependent Variable, the Independent Variable and the Controlled Variable?

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The difference between the independent, dependent and control variables rests with the way each variable impacts research. The dependent variable is the item under observation, the independent variable receives manipulation by a researcher and the control variable is an aspect that affects the dependent variable if the researcher does not hold it constant, explains Nuffield Foundation. These variables form the basis of an experiment or observation.

The dependent variable is the result of the study, explain researchers at the University of North Carolina at Pembroke. The dependent variable shows the effect of each independent variable. Researchers believe that the independent variables in a study explain the change in the outcome or dependent variable.

For example, in a study about the effect of extra-curricular programs and the completion of high school, each program is an independent variable, while the graduation rate is the dependent variable. The independent variable is the cause, and the dependent variable is the effect. Common control variables that affect the outcome of the dependent variable include the history of events and subjects, the type of assignment selection for the subjects and the design of the study that interferes with results and variables in the pre-test, according to California State University, Long Beach. Researchers measure the control variables if they believe there is an effect.