Which variable's value is affected by another variable in an experiment?

The dependent variable is the one whose value is affected by changes in another variable, specifically the independent variable. In an experiment, the independent variable is the one that the experimenter manipulates. As a result of this manipulation, the dependent variable is observed and measured to see how it responds. This relationship is fundamental to experimental design, as it allows researchers to determine effects and draw conclusions from their data.

For example, if a scientist is studying the effect of different amounts of sunlight on plant growth, the amount of sunlight is the independent variable, and the growth of the plant (measured in height or biomass) is the dependent variable. Any changes in the plant growth can be attributed to variations in sunlight exposure, thus illustrating the dependence of the measured outcome on the manipulation of the independent variable.

In this context, the control variable refers to factors that are kept constant so they do not affect the outcome, while the constant variable represents elements that remain unchanged. Neither of these plays a role in demonstrating the cause-and-effect relationship that the dependent variable provides in relation to the independent variable.