What Is an Independent Variable? Definition and Examples
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 about what independent variables are and how they work in research contexts can help you know how to identify them and use them in your own research studies. In this article, we define what an independent variable is, explain why it's important, describe how it's used and offer some examples to help you identify and apply them in 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 look to understand cause-and-effect relationships between two or more conditions. To identify how specific conditions affect others, researchers define independent and dependent variables. The independent variable is the condition that acts on the dependent variable, and the dependent variable is the condition that the researchers measure to understand the degree to which the independent variable causes an effect. By understanding the relationships between these variables, scientists can draw reasonable conclusions about how different values affect each other.
For example, if a pharmacologist wanted to measure the effectiveness of a new medication on relieving cold symptoms, they would design an experiment in which they administer the drug and measure the extent to which it relieves the participant's 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. By minimizing the potential for any external factors to affect the experiment, the pharmacologist can reasonably conclude that changes to the dependent variable result from 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 variables on the dependent variable to understand to what degree the independent variable influences the dependent variable. By eliminating external influences, scientists can draw sound conclusions about these relationships.
When to use independent variables
In general, researchers use independent variables whenever conducting an experiment. Even informal experiments typically have independent and dependent variables. For example, if you notice you have blisters on your feet after your daily run, you may conduct an informal experiment to test which of your running shoes are the best for foot comfort. In this experiment, the independent variables are the shoes and the dependent variables are your feet. 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 next week.
Although informal, the experiment allows you to gather evidence and draw conclusions about which shoes are better for your feet. Your shoes function as the independent variable because they create an effect on the dependent variable, your feet. Variables also work this way in more formal experiments. A formal experiment may also implement more controls to prevent external factors from influencing the results. For example, wearing the same type of sock every day and running at the same rate for the same time and distance minimizes the number of external variables that may confound the results of your experiment.
Examples of independent variables
Here are a few additional examples of independent variables used in different research contexts:
In an organization
Many businesses use extensive market research practices to understand their target customers and consumer behaviors. They also apply formal research methods when looking to improve their strategy for reaching and serving their customers. For example, a business looking to update its online store may test several page layout options with a focus group that represents its core customer base. Their goal is to make the page more efficient and reduce the time customers need to spend on the page to complete their transactions.
In this experiment, the independent variable is the page layout and the dependent variable is time spent on the page. By changing the page layout, the business hopes to influence how much time the users spend on the page. Since the time spent on the page depends on the page layout, the business can test multiple layouts and assess how each one affects the user's time.
In the workplace
In addition to its use in market research, independent variables can help businesses improve their workplace processes. The human resources department of a business often assesses the effectiveness of its current policies and plans revisions to improve workflows. For example, if the human resources department notices that employee productivity declines around a certain time each day, they 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.
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, they identify the independent variable as early childhood attachment, since they predict that attachment styles influence adult anxiety. They collect information about the study 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
A final example of independent variables in research applies to medical studies. 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. Since the researcher wants to understand how the medication causes an effect on the subject's health, the subject's health depends on the influence of the medication.
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