Dependent variables are a crucial part of conducting research studies. Researchers use the dependent variable to examine a hypothesis and advance their research.
Learning how to identify and select a dependent variable can help you design effective studies.
In this article, we discuss what a dependent variable is, how to identify one, how to choose them when planning a study, and provide examples of dependent variables.
Dependent Variable
The dependent variable is the one being measured or tested in an experiment. Unlike the independent variable, it depends on other factors.
For example, in research examining the effect of tutoring on test scores, the dependent variable would be the participants’ test scores since that is the focus of measurement, while the independent variable would be the tutoring.
A dependent variable is a factor in an experiment that changes based on the independent variable, which is the factor a researcher can manipulate during a study.
Researchers analyze the dependent variable to understand how the independent variable influences it directly.
Unlike the independent variable, researchers do not manipulate the dependent variable during an experiment.
In mathematical equations, the dependent variable is often represented as “y.” It is also called a response variable, outcome variable, or left-hand-side variable.
The dependent variable is termed “dependent” because it is believed to depend on the variations of the independent variable.
Examples of Dependent Variable
When learning to identify dependent variables in an experiment, it can be helpful to look at examples.
Here are a few examples of dependent variables in psychology research:
Influence of Study Time on Test Scores
How does the amount of time spent studying influence test scores?
In this case, test scores would be the dependent variable, and the amount of studying would be the independent variable. The researcher could also vary the independent variable by evaluating how age or gender influences test scores.
Impact of Stress on Memory
How does stress influence memory? Here, the dependent variable might be scores on a memory test, while the independent variable might be exposure to a stressful task.
Effect of Therapeutic Techniques on Psychological Symptoms
How does a specific therapeutic technique influence the symptoms of psychological disorders? In this scenario, the dependent variable might be the severity of the symptoms a patient is experiencing, and the independent variable would be the use of a specific therapy method.
Classical Music and Math Exam Performance
Does listening to classical music help students perform better on a math exam? The dependent variable is the scores on the math exams, and the independent variable is the classical music.
Response Time to Different Sounds
How long does it take people to respond to different sounds? The dependent variable is the length of time it takes participants to respond to a sound, while the sounds are the independent variable.
Language Learning in First-Born vs. Second-Born Children
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.
Alcohol Use and Reaction Time While Driving
How does alcohol use influence reaction time while driving?
The independent variable is the amount of alcohol a participant ingests, while their performance on the driving test is the dependent variable.
Selecting a Dependent Variable
To select a dependent variable for testing, follow these steps:
- Define what you aim to measure. Consider the experiment’s purpose and the hypothesis you want to test. Create a hypothesis statement and identify the variables that can test that hypothesis.
- Determine the independent variable. Since the dependent variable relies on the independent variable, start by choosing the independent variable. This variable is not directly tested but can be adjusted to measure the study’s outcomes.
- Select the dependent variable. Once you have identified the independent variable, consider the study’s purpose and what you intend to measure. The primary variable to test is the dependent variable, as it reflects the impact of the independent variable. For instance, if studying how a student’s sleep hours affect their GPA, GPA becomes the dependent variable as it changes with varying sleep durations.
- Conduct the experiment. With the independent and dependent variables defined, start testing. Adjust the study as needed to gather relevant data. Analyze the data to understand how manipulating the independent variable influences the dependent variable.
- Stability Stability is an essential criterion for a high-quality dependent variable. If the experiment is repeated with the same participants, conditions, and experimental manipulations, the effects on the dependent variable should closely match the initial results.
- Complexity Researchers may also select dependent variables based on the complexity of their study. While some studies involve only one dependent variable and one independent variable, it is possible to have several of each type. Researchers might want to learn how changes in a single independent variable affect multiple dependent variables. For instance, in an experiment examining how the messiness of a room influences people’s creativity levels and mood, the messiness of the room would be the independent variable, while creativity levels and mood would be the dependent variables.
- Ability to Operationalize Operationalization involves translating a construct into its measurable form. A good dependent variable is one that can be effectively measured. For example, to measure burnout, researchers might use the Maslach Burnout Inventory. To measure depression, they could use the Patient Health Questionnaire-9 (PHQ-9).
For example, if investigating how sleep hours impact GPAs, participants could report their nightly sleep hours. Adjust the study to focus on sleep hours on school days, affecting how sleep duration influences GPA, the dependent variable.
Conclusion
Understanding what a dependent variable is and how it is used can be helpful for interpreting various types of research you may 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.