- Science, Tech, Math ›
- Chemistry ›
Examples of Independent and Dependent Variables
What Are Independent and Dependent Variables?
- Chemical Laws
- Periodic Table
- Projects & Experiments
- Scientific Method
- Biochemistry
- Physical Chemistry
- Medical Chemistry
- Chemistry In Everyday Life
- Famous Chemists
- Activities for Kids
- Abbreviations & Acronyms
- Weather & Climate
- Ph.D., Biomedical Sciences, University of Tennessee at Knoxville
- B.A., Physics and Mathematics, Hastings College
Both the independent variable and dependent variable are examined in an experiment using the scientific method , so it's important to know what they are and how to use them.
In a scientific experiment, you'll ultimately be changing or controlling the independent variable and measuring the effect on the dependent variable. This distinction is critical in evaluating and proving hypotheses.
Below you'll find more about these two types of variables, along with examples of each in sample science experiments, and an explanation of how to graph them to help visualize your data.
What Is an Independent Variable?
An independent variable is the condition that you change in an experiment. In other words, it is the variable you control. It is called independent because its value does not depend on and is not affected by the state of any other variable in the experiment. Sometimes you may hear this variable called the "controlled variable" because it is the one that is changed. Do not confuse it with a control variable , which is a variable that is purposely held constant so that it can't affect the outcome of the experiment.
- What Is a Dependent Variable?
The dependent variable is the condition that you measure in an experiment. You are assessing how it responds to a change in the independent variable, so you can think of it as depending on the independent variable. Sometimes the dependent variable is called the "responding variable."
Independent and Dependent Variable Examples
- In a study to determine whether the amount of time a student sleeps affects test scores, the independent variable is the amount of time spent sleeping while the dependent variable is the test score.
- You want to compare brands of paper towels to see which holds the most liquid. The independent variable in your experiment would be the brand of paper towels. The dependent variable would be the amount of liquid absorbed by the paper towel.
- In an experiment to determine how far people can see into the infrared part of the spectrum, the wavelength of light is the independent variable and whether the light is observed (the response) is the dependent variable.
- If you want to know whether caffeine affects your appetite, the presence or absence of a given amount of caffeine would be the independent variable. How hungry you are would be the dependent variable.
- You want to determine whether a chemical is essential for rat nutrition, so you design an experiment. The presence or absence of the chemical is the independent variable. The health of the rat (whether it lives and can reproduce) is the dependent variable. If you determine the substance is necessary for proper nutrition, a follow-up experiment might determine how much of the chemical is needed. Here, the amount of the chemical would be the independent variable, and the rat's health would be the dependent variable.
How Do You Tell Independent and Dependent Variables Apart?
If you are having a hard time identifying which variable is the independent variable and which is the dependent variable, remember the dependent variable is the one affected by a change in the independent variable. If you write out the variables in a sentence that shows cause and effect, the independent variable causes the effect on the dependent variable. If you have the variables in the wrong order, the sentence won't make sense.
Independent variable causes an effect on the dependent variable.
Example : How long you sleep (independent variable) affects your test score (dependent variable).
This makes sense, but:
Example : Your test score affects how long you sleep.
This doesn't really make sense (unless you can't sleep because you are worried you failed a test, but that would be a different experiment).
How to Plot Variables on a Graph
There is a standard method for graphing independent and dependent variables. The x-axis is the independent variable, while the y-axis is the dependent variable. You can use the DRY MIX acronym to help remember how to graph variables:
D = dependent variable R = responding variable Y = graph on the vertical or y-axis
M = manipulated variable I = independent variable X = graph on the horizontal or x-axis
Test your understanding with the scientific method quiz .
Key Takeaways
- In scientific experiments, the independent variable is manipulated while the dependent variable is measured.
- The independent variable, controlled by the experimenter, influences the dependent variable, which responds to changes. This dynamic forms the basis of cause-and-effect relationships.
- Graphing independent and dependent variables follows a standard method in which the independent variable is plotted on the x-axis and the dependent variable on the y-axis.
- Difference Between Independent and Dependent Variables
- The Difference Between Control Group and Experimental Group
- How to Write a Lab Report
- What Is an Experiment? Definition and Design
- How To Design a Science Fair Experiment
- Boiling Points of Ethanol, Methanol, and Isopropyl Alcohol
- Understanding Experimental Groups
- 10 Examples of Heterogeneous and Homogeneous Mixtures
- The Difference Between Homogeneous and Heterogeneous Mixtures
- The Difference Between Intensive and Extensive Properties
- Chemical Properties of Matter
- What Is a Molecule?
- Examples of Physical Changes
- Commensalism Definition, Examples, and Relationships
- Acidic Solution Definition
IMAGES
VIDEO