DEPENDENT AND INDEPENDENT VARIABLES: CONCEPT AND EXAMPLES - SCIENCE - 2025

The dependent and independent variables are the two main variables of any experiment or investigation. The independent (VI) is the one that changes or is controlled to study its effects on the dependent variable (VD). The dependent is the variable that is investigated and measured.

They can then be seen as cause (independent variable) and effect (dependent variable). The independent is controlled by the experimenter, while the dependent changes in response to the independent. We are going to put an example:

We want to do a study to study the effects of alcohol consumption on blood pressure. The amount of alcohol consumed daily would be the independent variable (cause) and blood pressure would be the dependent variable (effect).

Other examples:

-Effects of tobacco on physical resistance. Tobacco consumption (VI), physical resistance (DV).

-Effects of sugar consumption on weight. Sugar consumption (VI), weight (DV).

In this article on the scientific method you can learn more about how these variables are used in scientific investigations.

Concept of independent variable and dependent variable, how to identify them?

Independent variable

The independent variable (VI) is the one that changes or is controlled to see its effects on the dependent variable (VD). For example, a study wants to measure the effects of height on weight. Height is VI and weight is RV.

It can stand on its own and is not affected by anything the experimenter does or by another variable within the experiment itself; hence its name "independent".

It is the variable that can be systematically managed or manipulated by the experimenter, whose controlled changes have a direct effect on the dependent variable.

Speaking from the mathematical point of view, they are the input elements to the equation or study model and it is represented in the abscissa (x) axis in a graph.

In other words, it is the supposed "cause" in the relationship being studied. Generally, only one is chosen as the independent variable to avoid that several factors at the same time have effects on the dependent variable.

If that happened, it would be difficult to identify and measure which of the modifications in the "independent" variables is causing changes in observed behavior.

The independent variable is also known as a controlled variable or predictive variable depending on the type of study.

Dependent variable

The dependent variable (VD) is the one that is affected by the independent variable (VD). It's about the effect, what is measured. For example, in a study you want to measure the amount of sun that a plant receives and its height. The amount of sun is the VI, it is the cause. The height of the plant would be the DV, the effect that is measured.

It is the focus of the overall study in which the experimenter focuses his observations and measurements, to see how his behavior responds to controlled changes. In other words, it is the presumed "effect" of the relationship studied.

It is represented on the axis of the ordinate (y) of a graph, since they are the output elements of a functional model or equation. The changes observed in this variable are meticulously recorded as a fundamental part of the results of the experiment.

Depending on the type of study, it can also be known as an experimental variable, measurement variable, or response variable.

Identifying dependent and independent variables (with examples)

The simple name of "dependent" or "independent" could give the impression of not needing further explanation to understand its nature, since its definitions seem to be very easy and universal.

Especially in the social or behavioral sciences, the correct identification of study variables can be confusing or not so obvious. For this reason, it is extremely important to manage differences to ensure that the results are relevant and meaningful.

Many scholars do not recommend using the terms "dependent" and "independent" for studies that are not experimental or in line with the scientific method.

Even so, they are still part of the methodological approach most commonly used in research of a social nature.

The following exercise is a quick way to identify or differentiate the selected variables, inserting the names of the study variables into the sentence in a way that makes sense:

• The / He / Los causes a change in the / them, and it is impossible for the / him / them to cause changes in the / them.

Examples

1 - Using the following 2 variables from a study, "positive comments" and "self-esteem", with the suggested exercise, it would read as follows: Positive comments cause a change in self-esteem and it is impossible that self-esteem can cause changes in the positive comments.

From a more logical and scientific point of view, the above proposition makes a lot of sense and works to illustrate the identification and differentiation between dependent and independent variables.

As mentioned in previous points, with a much more in-depth study from the social or psychological point of view, it could be discussed the cases in which having a good self-esteem can cause positive effects on people that could translate into positive comments.

2- In "Exposure to more sunlight increases happiness levels in workers who stay in closed offices all day", using the suggested exercise, exposure to the sun would be the independent variable and the level of happiness would be the dependent variable.

The independent could be controlled with the exposure time (hours, days, weeks), and the dependent with a multiple scale where workers are asked at the end of the day simply how they feel.

3- In the question "What are the benefits or aggravating factors of social networks in children?", It is clearly possible to identify social networks as the independent variable, because it is assumed that it causes a beneficial or aggravating effect on children. This effect is what is proposed as the object of study, therefore it is the dependent variable.

4- How much water flows through a tap at different openings ?: The independent variable would be the opening of the water tap controlled as closed, slightly open, half open and fully open. The dependent variable would be the water flow measured in liters per minute.

5 - An electric motor rotates faster as the voltage increases: electricity voltage controlled in volts, independent variable. Rotation speed measured in revolutions per minute, dependent variable.

References

1. Karl L. Wuensc (2004). Independent Variables and Dependent Variables. East Carolina University - Department of Psychology. Recovered from core.ecu.edu.
2. Robert V. Labaree (2017). Organizing Your Social Sciences Research Paper: Independent and Dependent Variables. University of Southern California - USC Libraries - Research Guides. Recovered from libguides.usc.edu.
3. Todd Helmenstine (2017). What Is the Difference Between Independent and Dependent Variables? Independent vs Dependent Variables. ThoughtCO. Recovered from thoughtco.com.
4. Graphic Totorial what are independent and dependent variables? Recovered from nces.ed.gov.
5. Office of Research Integrity (ORI). Case example for Independent and Dependent variables. ORI Curriculum Examples - Basic Research Concepts. Recovered from ori.hhs.gov.
6. Science Buddies. Variables in Your Science Fair Project. Recovered from sciencebuddies.org.
7. Andale (2014). Dependent Variable: Definition and Examples / Independent Variable (Treatment Variable) Definition and Uses. Statistics How To. Recovered from statisticshowto.com.