The dependent variable is the variable that you study and measure in response to changes in the independent variable. In other words, it depends on the independent variable. Other names for the dependent variable are the responding variable or measured variable.
Dependent Variable Examples
For example, say you want to know whether the amount you eat changes from day to day. You can set this up as an experiment in which you record food ingested over time. You add up all the calories you eat during a day or you measure the mass of food per day. To get meaningful data, you carry out the project for a month. The amount of food depends on the day, so it is the dependent variable.
For another example, you decide to see whether heart rate is affected by temperature. In other words, if you change the temperature, then does it affect your heart rate? Temperature is the independent variable or the one you control. Your heart rate is the dependent variable, which you measure in response to a change in temperature.
How to Identify the Dependent Variable
To find the dependent variable, think of the experiment in terms of “if, then” or “cause and effect.” The dependent variable is the “then” or “effect.” If you change one thing (the independent variable), then there is a change in the other thing (the dependent variable). You can set or control the independent variable, but you can only observe and measure the dependent variable.
Graphing the Dependent Variable
When graphing data, the convention is to put the independent variable on the x-axis and the dependent variable on the y-axis. If you write an ordered pair to record data, the independent variable is given first, followed by the dependent variable [e.g., (0, 2)].
The acronym to remember is DRY:
D – Dependent variable
R – Responds to change
Y – Y-axis on a graph
References
- Hinkelmann, Klaus; Kempthorne, Oscar (2008). Design and Analysis of Experiments. Volume I: Introduction to Experimental Design (2nd ed.). Wiley. ISBN 978-0-471-72756-9.
- Quine, Willard V. (1960). “Variables Explained Away.” Proceedings of the American Philosophical Society. American Philosophical Society. 104 (3): 343–347.