What Is an Independent Variable? (With Uses and Examples)

Updated March 10, 2023

In a research study, scientists define independent and dependent variables to understand cause-and-effect relationships. They design controlled experimental settings in which they measure how independent variables influence dependent variables. Learning what independent variables are and how they work in research contexts can help you understand how to identify them in your own experiments.

In this article, we define what an independent variable is, explain how it differs from a dependent variable, describe when to use independent variables and provide examples to help you identify and apply them in your research.

What is an independent variable?

An independent variable is a condition in a research study that causes an effect on a dependent variable. In research, scientists try to understand cause-and-effect relationships between two or more conditions. To identify how specific conditions affect others, researchers define independent and dependent variables. By understanding the relationships between these variables, scientists can draw reasonable conclusions about how different values affect each other.

Independent variable vs. dependent variable

The independent variable is the condition that acts on the dependent variable. The dependent variable is the condition that researchers measure to understand the degree to which the independent variable causes an effect. Dependent variables are what scientists are testing or studying since they depend on another factor.

For example, if a pharmacologist wants to measure the effectiveness of a new medication in relieving cold symptoms, they would design an experiment in which they administer the drug and measure the extent to which it relieves participants' symptoms. In this experiment, the medication is the independent variable because it acts on the symptoms. The cold symptoms are the dependent variable because they depend on the influence of the independent variable.

Why are independent variables important?

Independent variables are essential to effective experimental design because they allow scientists to identify cause-and-effect relationships. In a controlled experiment, researchers work to minimize or eliminate the potential for external influences so they can make conclusions about how one variable influences another.

To achieve this goal, they define one or more independent variables, which they apply to the dependent variable. They then measure the effect of the independent variable on the dependent variable to understand the degree to which the independent variable influences the dependent variable. By eliminating external influences, scientists can draw reasonable conclusions about these relationships.

When to use independent variables

Researchers generally use independent variables when they're conducting an experiment. Even informal experiments typically have independent and dependent variables. For example, if you have blisters on your feet after your daily run, you may conduct an informal experiment to determine which of your running shoes is most comfortable. You may try wearing one pair of shoes for a week and assess how your feet feel after each run. Then, you may try another pair during the next week. In this experiment, the independent variables are the shoes and the dependent variables are your feet.

Independent variables also help you gather evidence and draw conclusions about a topic in more formal experiments. A formal experiment may implement more controls to prevent external factors from influencing the results. For example, a shoe company might conduct a formal experiment on the comfort of one line of shoes. The company's researchers may implement controls by having participants wear the same type of sock each day and run at the same rate for the same time and distance. This can help the researchers minimize the number of external variables that may affect the results of their experiment.

Examples of independent variables

Here are a few examples of independent variables used in different contexts:

In social science research

Social science researchers in psychology, sociology and criminology use independent and dependent variables to study the relationships between people and society. For example, a psychology researcher may develop an experiment to understand how early childhood attachment influences anxiety in adults.

In their experiment, the researcher identifies the independent variable as early childhood attachment, since they predict that attachment styles influence adult anxiety. They collect information about participants' attachment styles and correlate them with their anxiety levels to assess whether there's a significant cause-and-effect relationship between the variables.

In medical research

In pharmacy research, scientists use clinical studies to evaluate the effectiveness and safety of new medications. When testing the effectiveness of a new drug, the independent variable is the medication and the dependent variable is the health of the research subject. The researchers want to understand how the medication affects the subject's health, and their health depends on the influence of the medication.

In market research

Many businesses use market research practices to understand their target customers and consumer behaviors. They also apply formal research methods when looking to improve their strategy for finding and serving customers. For example, a business that wants to update its online store may test several page layout options with a focus group that represents its core customer base. The business' goal is to make the page more efficient and reduce the time that customers need to spend to complete their transactions.

In this experiment, the independent variable is the page layout and the dependent variable is the time spent on the page. By changing the page layout, the business hopes to influence how much time users spend on it. The business can test multiple layouts and assess how they affect each user's time on the page.

In the workplace

Using independent variables can also help businesses improve their work processes. For instance, the human resources department of a business may conduct experiments to assess the effectiveness of its current policies and plan revisions to improve workflows.

If the human resources department notices that employee productivity declines at a certain time each day, it may conduct an experiment to see if implementing a short, structured break period at the same time each afternoon improves employee productivity. In this experiment, the independent variable is the break period and the dependent variable is employee productivity.