What Are Dependent, Independent and Controlled Variable?


For example, if I want to know how gender and leadership style affects job satisfaction, participants’ age may influence the results. A controlled variable is one which the scientist holds constant (controls) during an experiment. Thus we also know the controlled variable as a constant variable or sometimes as a “control” only. Defining your variables, and deciding how you will manipulate and measure them, is an important part of experimental design.

It’s usually contrasted with deductive reasoning, where you proceed from general information to specific conclusions. There is a risk of an interviewer effect in all types of interviews, but it can be mitigated by writing really high-quality interview questions. Social desirability bias can be mitigated by ensuring participants feel at ease and comfortable sharing their views.

This can lead you to false conclusions (Type I and II errors) about the relationship between the variables you’re studying. With random error, multiple measurements will tend to cluster around the true value. When you’re collecting data from a large sample, the errors in different directions will cancel each other out. When designing or evaluating a measure, construct validity helps you ensure you’re actually measuring the construct you’re interested in. If you don’t have construct validity, you may inadvertently measure unrelated or distinct constructs and lose precision in your research. While experts have a deep understanding of research methods, the people you’re studying can provide you with valuable insights you may have missed otherwise.


Purposive and convenience sampling are both sampling methods that are typically used in qualitative data collection. The main difference is that in stratified sampling, you draw a random sample from each subgroup (probability sampling). In quota sampling you select a predetermined number or proportion of units, in a non-random manner (non-probability sampling). Because of this, not every member of the population has an equal chance of being included in the sample, giving rise to sampling bias. You measure the math skills of all participants using a standardized test and check whether they differ based on room temperature.

On the other hand, the scientist has no control on the students’ test scores. Students are often asked to identify the independent and dependent variable in an experiment. It’s even possible for the dependent variable to remain unchanged in response to controlling the independent variable. By practicing identifying independent variables in different scenarios, you’re becoming a true independent variable detective. Keep practicing, stay curious, and you’ll soon be spotting independent variables everywhere you go.

Once upon a time, in a world thirsty for understanding, people observed the stars, the seas, and everything in between, seeking to unlock the mysteries of the universe. Operational variables (or operationalizing definitions) refer to how you will define and measure a specific variable as it is used in your study. This enables another psychologist to replicate your research and is essential in establishing reliability (achieving consistency in the results). You need to know which types of variables you are working with in order to choose appropriate statistical tests and interpret the results of your study. Control variables are very important to mention in your research proposal and methods section so that you can take them into account when conducting your study. This method illustrates how you can operationalize variables to make them quantifiable.

  • Together, they help you evaluate whether a test measures the concept it was designed to measure.
  • Theoretically, the test results depend on breakfast, so the test results are the dependent variable.
  • Our vetted tutor database includes a range of experienced educators who can help you polish an essay for English or explain how derivatives work for Calculus.
  • Without independent variables, we wouldn’t have many of the advancements and understandings that we take for granted today.

The Basics of BuildingConstructing an experiment is like building a castle, and the independent variable is the cornerstone. It’s carefully chosen and manipulated to see how it affects the dependent variable. Researchers also identify control and confounding variables, ensuring the castle stands strong, and the results are reliable. Sometimes it is impossible to just change one variable, and in those cases, scientists rely on more-complicated mathematical analysis and additional experiments to try to figure out what is going on. Older students are invited to read more about that in our Experimental Design for Advanced Science Projects page.

Depending on your study topic, there are various other methods of controlling variables. In general, correlational research is high in external validity while experimental research is high in internal validity. Controlled experiments establish causality, whereas correlational studies only show associations between variables.

Role of the Independent Variable

In statistical research, a variable is defined as an attribute of an object of study. A dependent variable is the variable being tested and measured in a scientific experiment. The two main variables in an experiment are the independent and dependent variable. Although control variables may not be measured as they are not recorded, yet they can have a significant effect on the outcome of an experiment. A change in the independent variable i.e. amount of light directly causes a change in the dependent variable i.e. moth behaviour.

What about correlational research?

The correlation coefficient only tells you how closely your data fit on a line, so two datasets with the same correlation coefficient can have very different slopes. These considerations protect the rights of research participants, enhance research validity, and maintain scientific integrity. Research ethics matter for scientific integrity, human rights and dignity, and collaboration between science and society. These principles make sure that participation in studies is voluntary, informed, and safe. You can only guarantee anonymity by not collecting any personally identifying information—for example, names, phone numbers, email addresses, IP addresses, physical characteristics, photos, or videos. In this process, you review, analyze, detect, modify, or remove “dirty” data to make your dataset “clean.” Data cleaning is also called data cleansing or data scrubbing.

It can be a lot easier to understand the differences between these two variables with examples, so let’s look at some sample experiments below. Other examples of operationalized variables include the number of years in a career field, the percentage of time spent on certain activities, and working with other people. In a research design, you might operationalize control variables by defining them and measuring their value. Below are the key differences when looking at an independent variable vs. dependent variable. In mixed methods research, you use both qualitative and quantitative data collection and analysis methods to answer your research question.


It helps researchers create vaccines, understand social behaviors, explore ecological systems, and even develop new technologies. So, regardless of the type of data, researchers analyze the relationship between independent and dependent variables to gain insights into their research questions. In some studies, researchers may want to explore how multiple factors affect the outcome, so they include more than one independent variable. It’s considered the cause or factor that drives change, allowing psychologists to observe how it influences behavior, emotions, or other dependent variables in an experimental setting. Essentially, it’s the presumed cause in cause-and-effect relationships being studied.

If you didn’t have any constant variables, you wouldn’t be able to tell if the independent variable was what was really affecting the dependent variable. Both the independent variable and dependent variable are examined in an experiment using the scientific method, so it’s important to know what they are and how to use them. Here are the definitions for independent and dependent variables, examples of each variable, and the explanation for how to graph them. For another experiment, a scientist wants to determine whether one drug is more effective than another at controlling high blood pressure. The independent variable is the drug, while patient blood pressure is the dependent variable. In some ways, this experiment resembles the one with breakfast and test scores.

What are some ethical considerations related to independent and dependent variables?

After collecting data, you check for statistically significant differences between the groups. You find some and conclude that gender identity influences brain responses to infant cries. In research, variables are any characteristics that can online bookkeeping and accounting services take on different values, such as height, age, temperature, or test scores. There are of course other types of variables, and different ways to manipulate them called “schedules of reinforcement,” but we won’t get into that too much here.

However, in a different study, that same variable might be the one being measured or observed to understand its relationship with another variable, making it dependent. In the best experiments, the scientist must be able to measure the values for each variable. However, imagine trying to do an experiment where one of the variables is love. There is no such thing as a “love-meter.” You might have a belief that someone is in love, but you cannot really be sure, and you would probably have friends that do not agree with you. So, love is not measurable in a scientific sense; therefore, it would be a poor variable to use in an experiment.

They’re elements, characteristics, or behaviors that can shift or vary in different circumstances. Researchers should also consider the potential impact of their study on vulnerable populations and ensure that their methods are unbiased and free from discrimination. Operationalization has the advantage of generally providing a clear and objective definition of even complex variables.

Experiments are usually designed to find out what effect one variable has on another – in our example, the effect of salt addition on plant growth. I‘m a freelance content and SEO writer with a passion for finding the perfect combination of words to capture attention and express a message. I create catchy, SEO-friendly content for websites, blogs, articles, and social media.

About Me

Heather DeSantis is the CEO and Founder of Publicity For Good (PFG), Forbes 30 Under 30 nominee, PRNEWS Top Women in PR 2021 Entrepreneurs Award, Platinum PR Awards CEO Finalist 2021 and Ragan’s PR Daily Award – PR Leader of the Year for 2021 and has been working with CPG clients for nearly a decade.

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