A dependent variable is the variable being tested and measured in a scientific experiment. It is sometimes called the responding variable. The independent variable is the amount of light and the moth’s reaction is the dependent variable. A change in the independent variable (amount of light) directly causes a change in the dependent variable (moth behavior). The dependent variable depends on the independent variable. As the experimenter changes the independent variable, the change in the dependent variable is observed and recorded. For example, a scientist is testing the effect of light and dark on the behavior of moths by turning a light on and off. Another example of a dependent variable is a test score. How well you score on a test depends on other variables, such as how much you studied, the amount of sleep you had, whether you had breakfast and so on. In general, if you are studying the effect of a factor or the outcome, the effect or outcome is the dependent variable. If you measure the effect of temperature on flower color, temperature is the independent variable or the one you control, while the color of the flower is 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. For example, if you examine the effect of sleep on test score, the number of hours of sleep would be on the x-axis, while the test scores would be recorded on the y-axis of a graph.