What Is a Dependent Variable?

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What Is a Dependent Variable?

The dependent variable is the variable that is being measured or tested in an experiment. 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.

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

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

Independent Variable vs. Dependent Variable

Experiments can range from simple to quite complicated, so sometimes it can be a bit confusing to know how to identify the independent and 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.

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, the dependent variable would be test performance.

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.

For example, it's not uncommon for treatment-based studies to have some subjects receive a certain treatment while others receive no treatment at all. In this case, the treatment is an independent variable because it is the one being manipulated or changed.

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 resulting changes to the dependent variable.

How to Choose a Dependent Variable

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

Stability

Stability is often a good sign of a higher quality dependent variable. If the same 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.

Complexity

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

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." 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, the 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

As you are learning to identify the dependent variables in an experiment, it can be helpful to look at examples. Here are just a few examples of psychology research using dependent and independent variables.

  • How does the amount of time spent studying influence test scores? In this example, the amount of studying would be the independent variable and the test scores would be the dependent variable. The researcher could also change the independent variable by instead evaluating how age or gender influence test scores.
  • How does stress influence memory? In this example, 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? In this example, 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? In this example, 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 times while driving? The amount of alcohol a participant ingests is the independent variable, while their performance on the driving test is the dependent variable.

A Word From Verywell

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 you are 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 the y-axis on a graph. 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 course of the experiment. This enables researchers to more accurately assess the relationship between the dependent and independent variables. 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.

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