What is a Research Variable? Independent & Dependent

Noura Al Bistami, Devin Kowalczyk
  • Author
    Noura Al Bistami

    Noura has completed her MSc in Neuroscience from King's College London after receiving her BA in Psychology from the American University of Beirut. She is currently pursuing her career in Neuroscience, and has taught subjects pertaining to psychology, english literature, history, neuroscience, and neurobiology.

  • Instructor
    Devin Kowalczyk

    Devin has taught psychology and has a master's degree in clinical forensic psychology. He is working on his PhD.

Compare the independent variable and dependent variable in research. See other types of variables in research, including confounding and extraneous variables. Updated: 07/25/2021

Table of Contents


Variables in Research

The definition of a variable in the context of a research study is some feature with the potential to change, typically one that may influence or reflect a relationship or outcome. For example, potential variables might be time it takes for something to occur, whether or not an object is used within a study, or the presence of a feature among members of the sample.

Within research, independent and dependent variables are key, forming the basis on which a study is performed. However, other types of variables may come into play within a study, such as confounding variables, controlled variables, extraneous, and moderator variables.

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  • 0:09 Research
  • 1:15 Dependent and…
  • 2:41 Unwanted Influence
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Dependent Variables in Research

A dependent variable is one being measured in an experiment, reflecting an outcome. Researchers do not directly control this variable. Instead, they hope to learn something about the relationship between different variables by observing how the dependent variable reacts under different circumstances.

Although "dependent variable" is the most commonly used term, they may also be referred to as response variables, outcome variable, or left-hand-side variable. These alternate names help to further illustrate their purpose: a dependent variable shows a response to changes in other variables, displaying the outcome.

The meaning of "left-hand-side" is less immediately transparent, but becomes more obvious when considering the format of a basic algebraic equation. Typically, the dependent variable in these is referred to as "Y" and placed on the left-hand-side of the equation. Because of this standard, dependent variables may also be called the Y variable as well, and the dependent variable is usually seen on the y-axis in graphs.

One example of a dependent variable would be a student's test scores. Several factors would influence these scores, such as the amount of time spent studying, amount of sleep, or the stress levels of the student. Ultimately, the dependent variable is not static or controlled directly, but is subject to change depending on the independent variables involved.

Independent Variables in Research

An independent variable is one that the researcher controls or otherwise manipulates within a study. In order to determine the relationship between dependent and independent variables, a researcher will purposefully change an independent variable, watching to see if and how the dependent variable changes in response.

The independent variable can alternately be called the explanatory, predicator, right-hand-side, or X variable. Similarly to dependent variables, these reflect the uses of independent variables, as they are intended to explain or predict changes in the dependent variables. Likewise, independent variables are often referred to as "X" in basic algebraic equations and plotted using the x-axis. In research, the experimenters will generally control independent variables as much as possible, so that they can understand their true relationship with the dependent variables.

For example, a research study might use age as an independent variable, since it influences some potential dependent variables. Obviously, a researcher cannot randomly assign ages to participants, but they could only allow participants of certain ages into a study or sort a sample into desired age groups.

Comparing Dependent and Independent Variables

Research Topic Independent Variable Dependent Variable
All Research Topics Manipulated by the researcher. Measured by the researcher.
All Research Topics What is being changed. What is changing in response.
Plants grow faster in warmer temperatures. Temperature Plant Growth
To what extent does traffic affect a person's mood? Traffic Mood
People walk slower after drinking coffee. Drinking Coffee Walking Speed

Examples of Independent and Dependent Variables in Research Studies

Many research studies have independent and dependent variables, since understanding cause-and-effect between them is a key end goal. Some examples of research questions involving these variables include:

  • How does sleep the night before an exam affect scores in students? The independent variable is the amount of time slept (in hours), and the dependent variable is the test score.
  • How does caffeine affect hunger? The amount of caffeine consumed would be the independent variable, and hunger would be the dependent variable.
  • Is quality of sleep affected by phone use before bedtime? The length of time spent on the phone prior to sleeping would be the independent variable and the quality of sleep would be the dependent variable.
  • Does listening to classical music help young children develop their reading abilities? The frequency and level of classical music exposure would be the independent variables, and reading scores would be the dependent variable.

Coffee may affect hunger levels. To study this, coffee would be the independent variable and hunger would be the dependent variable.

A cup of coffee.

Other Types of Variables in Research

While the independent and dependent variables are the most commonly discussed variables in research, other variables can influence outcomes. These include confounding, extraneous, control, and moderator variables.

Confounding Variables

A confounding variable, also known as a "third variable," changes the dependent variable despite not being the independent variable being studied. This can cause issues within a study. After all, since variation in a confounding variable causes a response in a dependent variable, that response may be misattributed the independent variable. In order to ensure that the observed outcome is only due to changes in independent variables, it is crucial to determine what confounding variables might sway experimental results.

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Frequently Asked Questions

What is dependent and independent variable in research?

The dependent variable in a research study or experiment is what is being measured in the study or experiment.

The independent variable in a research study or experiment is what the researcher is changing in the study or experiment. It is the variable that is being manipulated.

The independent variable is responsible for changing the dependent variable.

What are variables in research examples?

A variable is something that can be measured in a study or experiment. The independent and dependent variable are vital to the understanding and development of research.

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