Independent and dependent variables are an essential part of well-designed research.
The independent variable refers to the factors that a researcher can manipulate or control. The dependent variable is concerned with what is tested or measured in an experiment.
The table below presents the definition of independent and dependent variables and other associated names in literature for each.
|Variable Type||Definition||In literature also known as:|
|The Independent Variable is a variable that the researcher can manipulate to determine if it impacts a dependent variable.||– Predictor variable|
– Treatment variable
|The Dependent Variable is the variable tested and measured in a study to identify if the independent variable impacts it.||– Results Variable|
– Outcome Variable
– Criterion Variable
Perhaps even more important than knowing what independent and dependent variables are, is understanding how to identify and use them in our study. If you are seeking to understand that, this article is for you.
In this article, you will learn:
- What are variables, and why do we use them in research
- What are independent variables, and how can we spot them
- Everything you need to know about dependent variables in your study
- Examples of independent and dependent variables in use
Let’s put aside the independent and dependent variables for a bit and start with the basics.
What is a variable?
As the name implies, a variable is something that varies. In other words, a variable is a data item that can hold more than one value. These values can be anything from names, addresses, numbers, etc.
Think, for instance, to human eyes. Any of the following values can express the eye color variable: blue, brown, amber, green, hazel, even red, or any combination of those.
Other examples of variables can be weight expressed in kilograms (e.g., 900 grams; 52 kg; 1 ton); gender (e.g., male, female, transgender); age (e.g., 9 months; 20 years; young; old), weather (e.g., temperature, air pressure, precipitation, humidity), etc.
Variables are practically used everywhere, from mathematics, computer science to statistical analysis and research.
Experimental research uses at least two types of variables: independent and dependent. Other types of variables are control variables, moderator variables, and extraneous variables.
In this article, we will focus on independent and dependent variables. Let’s start with the dependent variable first.
What are dependent variables?
Dependent variables are the variables you plan to test in your experiment. As the name implies, a dependent variable depends on something else, such as an independent variable.
We will cover independent variables in a moment. For now, just think of dependent variables as what is measured in a study.
Let’s look at some examples to make sure we get this right.
Let’s assume you test the difference between two groups (Group A and Group B) of respondents and how well they can remember ten given words after one day.
What is being tested is the number of words being memorized, which is the study’s dependent variable in this case.
Such studies can be conducted, e.g., when investigating the impact of sleep on memory retention between two groups with different sleeping patterns. Another application could be testing the efficacy of a memory supplement between various groups.
Assuming you are investigating the factors impacting internal communication (e.g., Face-to-face Communication, Board Memos, Texting) on employee engagement in an organization.
Can we identify the dependent variable just by reading this statement? Of course. The dependent variable is employee engagement because it represents an outcome, respectively, what is being tested in the study.
You can think of a dependent variable representing the effect of something else.
Now that we understand how to formulate and spot dependent variables, the obvious question would be: can we use multiple dependent variables in our study?
The answer is yes, and we should. A study can have a primary research question but use the opportunity to answer other related questions as well. This is a common practice of more extensive studies such as dissertations or research papers.
Even if you are focused on measuring the relationship between an independent variable and a primary dependent variable, you can have multiple research questions in one study.
There is something you should keep in mind, though. Your research questions should be closely related and focused on the research problem so that your dependent variables are part of the same underlying research theme.
Now that we understand what a dependent variable is let’s discuss independent variables and their role in research.
What are independent variables?
An independent variable, also known as the treatment variable, represents the variable that a researcher controls directly or indirectly to test its impact on a particular outcome.
Direct control means the researcher designed the levels of the independent variable, e.g., Method 1, 2, and 3 of learning English. Indirect control refers to naturally occurring factors and cannot be manipulated directly, e.g., age or gender.
Let’s look at the following example and understand the role independent variables play in research.
Assuming you are investigating the efficiency of three methods of learning to speak English for adults as follows:
- Method 1: using specialized English textbooks.
- Method 2: attending one-to-one English tuition classes.
- Method 3: following an online English course.
In this example, the method of learning is the study’s independent variable, which we can control by ourselves respectively the learning criteria defined in each method; and the dependent variable is the speaking score as the result of the experiment.
Let’s assume we are seeking to understand the impact of gender on leadership styles in an organization.
In this case, the independent variable is gender and consists of two levels, male and female, and the dependent variable is a leadership style (e.g., transactional leadership, transformational leadership, etc.).
The easiest way to identify the independent and dependent variables in a study is to look at them side by side.
For instance, every time the researcher manipulates anything or assigns respondents to groups depending on attributes such as gender, age, income, etc., that variable is the independent variable.
In contrast, when researchers examine whether specific factors affect the outcome, they look at the dependent variable.
Some studies are not looking into how two or more variables affect each other but rather if the variables are related.
For instance, there is nothing to manipulate if you are interested only in the relationship between how much someone is flying and aviophobia. In that sense, there are no independent variables.
How To Use Independent And Dependent Variables In A Research Paper?
Now that we understand what independent and dependent variables are, let’s discuss some essential criteria when choosing the variables for our next research project.
Well-designed research follows the scientific method guidelines and starts by posing a question and identifying the relevant factors required to answer it. You can read more about the scientific method, definition, and steps here and how it influences the quality of research.
These factors, namely the variables used in a study, are not selected by guessing but rather through a detailed analysis of the existing body of literature regarding the matter under investigation.
In other words, you must present the theoretical framework that explains why the research topic under investigation is relevant for being studied.
Let’s assume we investigate factors affecting the leadership style in an organization. We should start by looking into existing theories on leadership (e.g., Transactional Theory, Transformational Theory, Strong Man Theory, Behavioural Theory, etc.) to guide us in formulating the research question and identifying the factors required for answering it.
When identifying the independent variables for our research, it is crucial to ensure that they are independent of any other variable used in the study. Thus, the independent variable can give the most significant insight possible and avoid confounding (multiple variables competing to explain an effect).
The same applies when choosing our dependent variable. A good dependent variable is sensitive to changes applied to the independent variables in the same study.
The presumed relationship between the independent and dependent variables, namely the research hypotheses, conceptual framework, and theoretical framework of the study, shall be discussed in the Literature Review chapter of your research paper.
Here are some critical points about research variables you should keep in mind:
- A variable is a data item that can hold more than a single value.
- Independent variables are the variables that can be manipulated or controlled by the researcher.
- A dependent variable is a variable a researcher plans to measure. It represents the outcome of an experiment.
- The relation between independent and dependent variables can be seen as cause and effect.
- The existing theories and literature should explain your research variables.
- All variables, proposed hypotheses, and conceptual framework are discussed in the Literature Review chapter of a research paper.
Cite this article in your research paper: