What Is a Dependent Variable?

The dependent variable is the variable that is being measured or tested in an experiment.1 This is different than the independent variable, which is a variable that stands on its own. For example, in a study looking at how tutoring impacts test scores, the dependent variable would be the participants’ test scores since that is what is being measured and the independent variable would be tutoring.

Learn how to tell the difference between dependent and independent variables. We also share how dependent variables are selected in research and a few examples to increase your understanding of how these variables are used in real-life studies.

The dependent variable is called “dependent” because it is thought to depend, in some way, on the variations of the independent variable.

Independent vs. Dependent Variable

In a psychology experiment, researchers study how changes in one variable (the independent variable) change another variable (the dependent variable).2 Manipulating independent variables and measuring the effect on dependent variables allows researchers to draw conclusions about cause-and-effect relationships.

These experiments can range from simple to quite complicated, so it can sometimes be a bit confusing to know how to identify the independent vs. dependent variables. Here are a couple of questions to ask to help you learn which is which.

Which Variable Is the Experimenter Measuring?

Keep in mind that the dependent variable is the one being measured. So, if the experiment is trying to see how one variable affects another, the variable that is being affected is the dependent variable.3

In many psychology experiments and studies, the dependent variable is a measure of a certain aspect of a participant’s behavior. In an experiment looking at how sleep affects test performance, for instance, the dependent variable would be test performance.

One way to help identify the dependent variable is to remember that it depends on the independent variable. When researchers make changes to the independent variable, they then measure any changes to the dependent variable.

Which Variable Does the Experimenter Manipulate?

The independent variable is “independent” because the experimenters are free to vary it as they need. This might mean changing the amount, duration, or type of variable that the participants in the study receive as a treatment or condition.4

For example, it’s common for treatment-based studies to have some subjects receive a certain treatment while others receive no treatment at all (often called a sham or placebo treatment). In this case, the treatment is an independent variable because it is the one being manipulated or changed.

Independent Variable

Variable being manipulated
Doesn’t change based on other variables
Stands on its own

Dependent Variable

Variable being measured
May change based on other variables
Depends on other variables

How to Choose a Dependent Variable

How do researchers determine what will be a good dependent variable? There are a few key features a scientist might consider.

Stability

Stability is often a good sign of a higher-quality dependent variable. If the experiment is repeated with the same participants, conditions, and experimental manipulations, the effects on the dependent variable should be very close to what they were the first time around.5

Complexity

A researcher might also choose dependent variables based on the complexity of their study. While some studies only have one dependent variable and one independent variable, it is possible to have several of each type.6

Researchers might also want to learn how changes in a single independent variable affect several dependent variables. For example, imagine an experiment where a researcher wants to learn how the messiness of a room influences people’s creativity levels.

This research might also want to see how the messiness of a room might influence a person’s mood. The messiness of a room would be the independent variable and the study would have two dependent variables: level of creativity and mood.

Ability to Operationalize

Operationalization is defined as “translating a construct into its manifestation.”7 In simple terms, it refers to how a variable will be measured. So, a good dependent variable is one that you are able to measure.

If measuring burnout, for instance, researchers might decide to use the Maslach Burnout Inventory. If measuring depression, they could use the Patient Health Questionnaire-9 (PHQ-9).

Dependent Variable Examples

When learning to identify the dependent variables in an experiment, it can be helpful to look at examples. Here are just a few dependent variable examples in psychology research.

How does the amount of time spent studying influence test scores? The test scores would be the dependent variable and the amount of studying would be the independent variable. The researcher could also change the independent variable by instead evaluating how age or gender influences test scores.
How does stress influence memory? The dependent variable might be scores on a memory test and the independent variable might be exposure to a stressful task.
How does a specific therapeutic technique influence the symptoms of psychological disorders? In this case, the dependent variable might be defined as the severity of the symptoms a patient is experiencing, while the independent variable would be the use of a specific therapy method.
Does listening to classical music help students perform better on a math exam? The scores on the math exams are the dependent variable and classical music is the independent variable.
How long does it take people to respond to different sounds? The length of time it takes participants to respond to a sound is the dependent variable, while the sounds are the independent variable.
Do first-born children learn to speak at a younger age than second-born children? In this example, the dependent variable is the age at which the child learns to speak and the independent variable is whether the child is first- or second-born.
How does alcohol use influence reaction time while driving? The amount of alcohol a participant ingests is the independent variable, while their performance on the driving test is the dependent variable.

Takeaways

Understanding what a dependent variable is and how it is used can be helpful for interpreting different types of research that you encounter in different settings. When trying to determine which variables are which, remember that the independent variables are the cause while the dependent variables are the effect.

Frequently Asked Questions

What does the dependent variable depend on?
The dependent variable depends on the independent variable. Thus, if the independent variable changes, the dependent variable would likely change too.
Where does the dependent variable go on a graph?
The dependent variable is placed on a graph’s y-axis. This is the vertical line or the line that extends upward. The independent variable is placed on the graph’s x-axis or the horizontal line.
How do you find a dependent variable?
The dependent variable is the one being measured. If looking at how a lack of sleep affects mental health, for instance, mental health is the dependent variable. In a study that seeks to find the effects of supplements on mood, the participants’ mood is the dependent variable.
What is a controlled variable?
A controlled variable is a variable that doesn’t change during the experiment. This enables researchers to assess the relationship between the dependent and independent variables more accurately. For example, if trying to assess the impact of drinking green tea on memory, researchers might ask subjects to drink it at the same time of day. This would be a controlled variable.