Dependent variable

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In experimental design, a dependent variable is a factor whose values in different treatment conditions are compared. That is, the experimenter is interested in determining if the value of the dependent variable varies when the values of another variable – the independent variable – are varied, and by how much.

In simple terms, the independent variable is said to cause an apparent change in, or simply affect, the dependent variable. In analysis, researchers usually want to explain why the dependent variable has a given value. In research, the values of a dependent variable in different settings are usually compared.

For example, in a study of how different dosages of a drug are related to the severity of symptoms of a disease, a measure of the severity of the symptoms of the disease is a dependent variable and the administration of the drug in specified doses is the independent variable. Researcher will compare the different values of the dependent variable (severity of the symptoms) and attempt to draw a conclusion.

In the graphing of data, the dependent variable goes on the y-axis (see Cartesian coordinates).

Examples of dependent variables are:

  • How a tree is affected after being planted in saline soil. The independent variable is the type of soil or how saline it is. The dependent variable could be, for example, a measure of leaf size.

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