Independent variables are the variables that the experimenter changes to test their dependent variable.
For example, a scientist is testing the effect of light and dark on the behavior of moths by turning a light on and off. The independent variable is the amount of light and the moth's reaction is the dependent variable.
A change in the independent variable directly causes a change in the dependent variable.
If the dependent and independent variables are plotted on a graph, the x-axis would be the independent variable and the y-axis would be the dependent variable.
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What Is a Dependent Variable?
What Is a Control Group?
What Is an Experimental Group?