Terms and Terminology Relating to Explaining the Relationship Between Two Variables

  • Variable: An amount, quantity or number that can vary and change
  • An independent variable: A factor that has some influence or impact on the dependent variable
  • Dependent variable: The factor that changes as a result of the influence of the independent variable
  • Response variable: Alternative term for dependent variable
  • Control variable: The thing or things that are controlled and constant so that they do not impact on the dependent variable
  • Covariance: The relationship between two variables
  • Positive correlation: When both the independent and dependent variables increase together and at the same time and when both the independent and dependent variables decrease together and at the same time
  • Negative correlation: When one of the variables increases at the same time that the other variable decreases

Variables

These three basic types of variables are:

  1. Independent variables
  2. Dependent variables
  3. Extraneous variables

Independent Variables

An independent variable is the factor that has some influence or impact on the dependent variable.

Dependent Variables

A dependent variable is the factor that changes as a result of the influence of the independent variable. It is the behavior, outcome or characteristic that changes as a response to some manipulation. For this reason, a dependent variable is sometimes referred to as a response variable.

Below are some examples of independent and dependent variables:

  • Knowledge levels (dependent variable) after an educational class on stress management techniques (independent variable)
  • The levels of stress (dependent variable) relating to the increasing severity of a chronic, progressive disease or illness (independent variable)

Extraneous Variables

Extraneous variables, which are also called, interfering variables, are conditions that undesirably impact on the dependent variable. This undesirable impact on a dependent variable should be prevented with the elimination and/or minimization of all extraneous variables.

When variables are put on a graph, the independent variable, like time in the graph above, is typically shown along the horizontal x axis of the graph and the dependent variable, like speed which increases with time in the graph above is typically placed and shown along the y axis.

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