. J Exp Soc Psychol. These variables are created when you analyze data, not when you measure it. It can be difficult to separate the true effect of the independent variable from the effect of the confounding variable. Do not confuse it with a "control variable," which is a variable that is purposely held constant so that it can't affect the outcome of the experiment. Of course, there are a lot of issues to consider when conducting an experiment, but these are the basic principles. One of the most popular forms of regression analysis is linear regression, which allows you to establish a linear relationship between a dependent variable and one or more independent variables. In statistical research, a variable is defined as an attribute of an object of study. You need to know what type of variables you are working with to choose the right statistical test for your data and interpret your results. Whats the definition of an independent variable? Other variations of an experiment might include having multiple levels of the independent variable. In most math . Personal Disord. Bookshelf They randomly assign half of the participants to take the recommended dosage of their supplement every day for three months after each workout. 1. . Is the variable something that cannot be changed but that is not dependent on other variables in the experiment? Test your understanding with the scientific method quiz. Each athlete will run on a treadmill for one hour while their heart rate is tracked. For example: Your independent variable is social media use, and you assign groups to low, medium, and high levels of social media use to find out if there is a difference in hours of sleep per night. In this animal study, the independent variable would be car exhaust and the dependent variable would be amount of time to run a maze. They fill each mold with one of the different concrete mixtures. This can provide very valuable information when studying just about any subject. 2019;10(1):82-86. doi:10.4103/idoj.IDOJ_468_18. ANOVA tells you if the dependent variable changes according to the level of the independent variable. This includes rankings (e.g. Age is the independent variable. The health of the rat (whether it lives and can reproduce) is the dependent variable. Discrete and continuous variables are two types of quantitative variables: If you want to cite this source, you can copy and paste the citation or click the Cite this Scribbr article button to automatically add the citation to our free Citation Generator. Scribbr. Fact checkers review articles for factual accuracy, relevance, and timeliness. Indian Dermatol Online J. In this example, the independent variable is Gatorade, and the dependent variable is heart rate. *Note that sometimes a variable can work as more than one type! Because it would be unethical to expose a randomized group of people to high levels of vehicle exhaust,[1] a study comparing two populations with differential exposure to vehicle exhaust would rely on a natural experiment, or a situation in which this already occurs due to factors unrelated to the researchers. (2022, December 02). Lack of sleep significantly affects learning in 10-year-old boys. 2018 Jan;9(1):12-21. doi: 10.1037/per0000254. The water temperature is the independent variable. The independent variable is the variable the experimenter manipulates or changes and is assumed to directly affect the dependent variable. If they can back up that claim with hard scientific data, that would be great for sales. No. confounds; dependent variable; independent variable; levels of measurement; mediation; moderation; risk factors. Be careful with these, because confounding variables run a high risk of introducing a variety of. In this study, the independent variable is meditation and the dependent variable is the amount of stress (however it is measured). It's the outcome you're interested in measuring, and it 'depends' on your independent variable. Seekprofessional input on your specific circumstances. You want to determine whether a chemical is essential for rat nutrition, so you design an experiment. A confounding variable is related to both the supposed cause and the supposed effect of the study. Copyright 2023 Helpful Professor. Generally, the independent variable goes on the x-axis (horizontal) and the dependent variable on the y-axis (vertical). An example of a dependent variable is how tall you are at different ages. Can graphic video games be a force for good? The Mozart Effect and the mathematical connection, Journal of College Reading and Learning, 42(2), 51-66. https://doi.org/10.1080/10790195.2012.10850354. This is a quasi-experimental design because theres no random assignment. This helps you to have confidence that your dependent variable results come solely from the independent variable manipulation. Our website is not intended to be a substitute for professional medical advice, diagnosis, or treatment. In research, variables are any characteristics that can take on different values, such as height, age, temperature, or test scores. Kendra Cherry, MS, is an author and educational consultant focused on helping students learn about psychology. ___________________________________________________________. This example sheet is color-coded according to the type of variable: nominal, continuous, ordinal, and binary. In this example, the color of the office is the independent variable. In a study to determine whether how long a student sleeps affects test scores, the independent variable is the length of time spent sleeping while the dependent variable is the test score. Plausible alternative explanations are other factors that may cause the dependent variable under observation.[4]. Can graphic video games be a force for good? Use this list of questions to check whether youre dealing with an independent variable: Check whether youre dealing with a dependent variable: Independent and dependent variables are generally used in experimental and quasi-experimental research. Accessibility Car pollution is a concern for a lot of reasons. Next, we randomly assign each person to either practice meditation every day, three days a week, or not at all. It then proceeds to describe and discuss synonyms for the terms independent variable and dependent variable, including treatment, intervention, predictor, and risk factor, and synonyms for. BSc (Hons), Psychology, MSc, Psychology of Education. This article begins by defining the term variable and the terms independent variable and dependent variable, providing examples of each. An ordinal variable can also be used as a quantitative variable if the scale is numeric and doesnt need to be kept as discrete integers. Its the outcome youre interested in measuring, and it depends on your independent variable. The x-axis is the independent variable, while the y-axis is the dependent variable. With Doing this helps ensure that the experiments know exactly what they are looking at or manipulating, allowing them to measure it and determine if it is the IV that is causing changes in the DV. Variables that represent the outcome of the experiment. This can happen when another variable is closely related to a variable you are interested in, but you havent controlled it in your experiment. Sometimes the dependent variable is called the "responding variable.". Some people take vitamins every day. To ensure cause and effect are established, it is important that we identify exactly how the independent and dependent variables will be measured; this is known as operationalizing the variables. In a study to determine whether how long a student sleeps affects test scores, the independent variable is the length of time spent sleeping while the dependent variable is the test score. I.V._____________________________________________________________, D.V. Saul Mcleod, Ph.D., is a qualified psychology teacher with over 18 years experience of working in further and higher education. For example, if we want to explore whether high concentrations of vehicle exhaust impact incidence of asthma in children, vehicle exhaust is the independent variable while asthma is the dependent variable. Is the researcher trying to understand whether or how this variable affects another variable? She has previously worked in healthcare and educational sectors. When you do correlational research, the terms dependent and independent dont apply, because you are not trying to establish a cause and effect relationship (causation). Measurements of continuous or non-finite values. Type of light the tomato plant is grown under, Presence or absence of intermittent fasting, Presence or absence of medical marijuana use, Type of work environment (remote or in office). One room is painted mostly white with red trim and seats; one room is painted mostly white with blue trim and seats; and one room is painted mostly white with off-white trim and seats. For example, gender identity, ethnicity, race, income, and education are all important subject variables that social researchers treat as independent variables. A group of health scientists decides to conduct a study to determine if taking vitamins improves health. PMC When you collect quantitative data, the numbers you record represent real amounts that can be added, subtracted, divided, etc. Their R&D food scientists have developed a protein supplement that is designed to help build muscle mass for people that work out regularly. If we didnt do this, then it would be very difficult (if not impossible) to compare the findings of different studies to the same behavior. Although there are many types of bias, two common types are selection bias and information bias. You have three independent variable levels, and each group gets a different level of treatment. You can email the site owner to let them know you were blocked. The independent variable is one that the researchers either manipulate (such as the amount of something) or that already exists but is not dependent upon other variables (such as the age of the participants). Researchers want to determine if a new type of treatment will lead to a reduction in anxiety for patients living with social phobia. A large multinational cosmetics company wants to know if the color of a womans hair affects the level of perceived attractiveness in males. How should we measure stress? The site is secure. Studentsshould always cross-check any information on this site with their course teacher. 2. Information biasrefers to a systematic error due to inaccurate measurement or classification of disease, exposure, or other variables.[3] Recall bias, a type of information bias, occurs when study participants do not remember the information they report accurately or completely. Data is generally divided into two categories: A variable that contains quantitative data is a quantitative variable; a variable that contains categorical data is a categorical variable. At first, many people in the industry didnt think airbags would be effective at all. One way to determine whether a relationship between variables is causal is based on three criteria for research design:temporal precedence meaning that the hypothesized cause happens before the measured effect;covariation of the cause and effect meaning that there is an established relationship between the two variables regardless of causation; and a lack of plausible alternative explanations. ThoughtCo, Aug. 27, 2020, thoughtco.com/independent-and-dependent-variable-examples-606828. Because the researcher controls the level of the independent variable, it can be determined if the independent variable has a causal effect on the dependent variable. Definition and examples of dependent variable Independent variables are the ones we can freely manipulate, by plugging in any input value. Afterward, their level of aggression was measured via a wide range of methods, including direct observations of their behavior, their actions when given the opportunity to be aggressive, or a variety of other measures. J Health Care Chaplain. If you are designing an experiment, here are a few tips for choosing an independent variable (or variables): It is also important to be aware that there may be other variables that might influence the results of an experiment. Learn more about our academic and editorial standards. If you want to know whether caffeine affects your appetite, the presence/absence of a given amount of caffeine would be the independent variable. Its called independent because its not influenced by any other variables in the study. An independent variable (IV) is what is manipulated in a scientific experiment to determine its effect on the dependent variable (DV). Independent variable causes an effect on the dependent variable. Nominal, Categorical, Dichotomous, Binary. Please include what you were doing when this page came up and the Cloudflare Ray ID found at the bottom of this page. A lot of those studies used an experimental design that involved males of various ages randomly assigned to play a graphic or non-graphic video game. One is called the dependent variable, and the other is the independent variable. A follow-up experiment might determine how much of the chemical is needed. This is because individuals that had a particularly bad (or good) experience with the physician may be more likely to go to the website and provide a rating. The dependent variable is the outcome (or response) variable. They then indicate how much they liked it by pressing one of 5 buttons: didnt like at all, liked, somewhat liked, liked very much, loved it. Yes, but including more than one of either type requires multiple research questions. A correlation reflects the strength and/or direction of the relationship between two (or more) variables. Categorical variables represent groupings of some kind. At the outset of an experiment, it is important for researchers to operationally define the independent variable. Is the variable one that is being manipulated by the experimenters? Here are several examples of independent and dependent variables in experiments: In a study to determine whether how long a student sleeps affects test scores, the independent variable is the length of time spent sleeping while the dependent variable is the test score. A confounding variable, also called a confounder or confounding factor, is a third variable in a study examining a potential cause-and-effect relationship. Cloudflare Ray ID: 7a29bcd96f01c31d There are several actions that could trigger this block including submitting a certain word or phrase, a SQL command or malformed data. 8600 Rockville Pike In addition, the article links terminology about variables with the concept of levels of measurement in research. Vehicle Exhaust and Cognitive Performance, Mastery Learning: 10 Examples, Strengths & Limitations. You want to know which brand of microwave popcorn pops the best. It then proceeds to describe and discuss synonyms for the terms independent variable and dependent variable, including treatment, intervention, predictor, and risk factor, and synonyms for dependent variable, such as response variables and outcomes. Revised on December 5, 2022. Example one: How long you use your phone before bed affects your quality of sleep. Its essential to know which is the cause the independent variable and which is the effect the dependent variable. The dependent variable is the variable being tested and measured in an experiment and is dependent on the independent variable. The independent variables in a particular experiment all depend on the hypothesis and what the experimenters are investigating. Federal government websites often end in .gov or .mil. Here are some examples of research questions and corresponding independent and dependent variables. At the end of one year, the health of all participants is assessed, using blood pressure and cholesterol level as the key measurements. Independent variables are defined as those the values of which influence other variables. The researchers then compare the scores of the exams between the two groups of classrooms. Each participant sits in front of a computer screen and responds to questions on a survey. To ensure the internal validity of an experiment, you should only change one independent variable at a time. Sometimes varying the independent variables will result in changes in the dependent variables. Gatorade and Improved Athletic Performance, 15. Helmenstine, Anne Marie, Ph.D. "What Are Independent and Dependent Variables?" You can think of independent and dependent variables in terms of cause and effect: an independent variable is the variable you think is the cause, while a dependent variable is the effect. Other research methodologies can reveal factors that are related to the dependent variable or associated with the dependent variable, but only when the independent variable is controlled by the researcher can causality be determined. Epub 2022 Mar 25. The action you just performed triggered the security solution. The independent variable is the teaching method, and the dependent variable is performance on the critical thinking test. Below is an example of using independent and dependent variables in an ecological study: A government agency handles environmental care in a city. So many studies have used so many different ways of measuring aggression. Example: How long you sleep (independent variable) affects your test score (dependent variable). The independent variable is the level of crust crunchiness, and the dependent variable is how much it was liked. For example, age, sex, current smoking, LDL cholesterol level, and blood pressure are independent variables because their values (e.g., greater age, positive for current smoking, and higher LDL cholesterol level) influence the risk of myocardial infarction. If you want to cite this source, you can copy and paste the citation or click the Cite this Scribbr article button to automatically add the citation to our free Citation Generator. Chaplaincy research: its value, its quality, and its future. They enlist the cooperation of over 120 gym rats that work out 5 days a week. Bethesda, MD 20894, Web Policies Read our, Introduction to Psychology Research Methods, Internal Validity vs. In this issue of Anesthesia & Analgesia, Mller-Wirtz et al 1 report results of a study in which they used linear regression to assess the relationship in a rat model between tissue propofol . It represents the cause or reason for an outcome. An independent variable is the variable you manipulate or vary in an experimental study to explore its effects. Another way to put it is the dependent variable is the output value and the independent variable is the input value. In an experiment, some volunteers receive the new treatment, another group receives a different treatment, and a third group receives no treatment. Researchers are trying to determine if changes to the independent variable (studying) result in significant changes to the dependent variable (the test results). In an experiment on the effects of the type of diet on weight loss, for example, researchers might look at several different types of diet. In an experiment to determine how far people can see into the infrared part of the spectrum, the wavelength of light is the independent variable and whether the light is observed (the response) is the dependent variable. Predictor variables (they can be used to predict the value of a dependent variable), Right-hand-side variables (they appear on the right-hand side of a, Outcome variables (they represent the outcome you want to measure), Left-hand-side variables (they appear on the left-hand side of a regression equation). The dependent variable is the biomass of the crops at harvest time. Select independent variables that you think will cause changes in another variable. Does this variable get measured only after other variables are altered? and transmitted securely. When running a study or analyzing statistics, researchers try to remove or account for as many of the confounding variables as possible in their study design or analysis. Independent vs. An example of a dependent variable is depression symptoms, which depends on the independent variable (type of therapy). The researchers believe that larger dilation indicates greater perceived attractiveness. While the study participants are sleeping, their heart rates and amount of time spent in deep sleep are recorded with high-tech equipment. The independent variable is the cause, and the dependent variable is the effect. Simply Scholar Ltd. 20-22 Wenlock Road, London N1 7GU, 2023 Simply Scholar, Ltd. All rights reserved, Variables are given a special name that only applies to. It must be either the cause or the effect, not both! J Health Care Chaplain. Blazing Angels or Resident Evil? So for y=x+3, when you input x=2, the output is y = 5. As an Amazon Associate I earn from qualifying purchases. Independent variables are what we expect will influence dependent variables. 2016 Sep;66:29-38. doi: 10.1016/j.jesp.2015.09.012. government site. Statistical models will estimate effect sizes for the independent variables. It then proceeds to describe and discuss synonyms for the terms independent variable and dependent variable, including treatment, intervention, predictor, and risk factor, and synonyms for dependent variable, such as response variables and outcomes. Distinguishing between independent and dependent variables can be tricky when designing a complex study or reading an academic research paper. Sometimes you may hear this variable called the "controlled variable" because it is the one that is changed. Because the scientists have an unlimited budget (and because this is a hypothetical example, all of the participants have the same meals delivered to their homes (breakfast, lunch, and dinner), every day for one year. A chemicals company has developed three different versions of their concrete mix. So, they rent space in a large shopping mall and create three different simulated restaurant interiors of different colors. https://doi.org/10.1080/08854726.2014.959374, Manocha, R., Black, D., Sarris, J., & Stough, C.(2011). Published on In these cases you may call the preceding variable (i.e., the rainfall) the predictor variable and the following variable (i.e. Variables that are held constant throughout the experiment. This article begins by defining the term variable and the terms independent variable and dependent variable, providing examples of each. [2] For example, an online website that rates the quality of primary care physicians based on patients input may produce ratings that suffer from selection bias. National Library of Medicine. Here are the definitions for independent and dependent variables, examples of each variable, and the explanation for how to graph them. An independent variable is defines as the variable that is changed or controlled in a scientific experiment. The health of the rat (whether it lives and reproduces) is the dependent variable. For example, in Darley . The independent variable is hair color, and the dependent variable is pupil dilation. 2023 Simply Psychology - Study Guides for Psychology Students. For the following hypotheses, name the IV and the DV and operationalize both variables. The conditions of each room are all exactly the same, except that half of the rooms have lavender released into the rooms and half do not. The dependent variable would be the amount of liquid absorbed by the paper towel. But there are many other ways of describing variables that help with interpreting your results. In these experimental studies, the independent variable was graphic video games, and the dependent variable was observed level of aggression. Helmenstine, Anne Marie, Ph.D. "What Are Independent and Dependent Variables?" You could also choose to look at the effect of exercise levels as well as diet, or even the additional effect of the two combined. The type of visualization you use depends on the variable types in your research questions: To inspect your data, you place your independent variable of treatment level on the x-axis and the dependent variable of blood pressure on the y-axis. All articles are edited by a PhD level academic. A variable that is made by combining multiple variables in an experiment. Confounding variables lead to bias, or a factor that may cause an estimate to differ from the true population value. National Library of Medicine Are you ready to take control of your mental health and relationship well-being? Published on This enables another psychologist to replicate your research and is essential in establishing reliability (achieving consistency in the results). Non-manipulation quantitative designs. Then, you select an appropriate statistical test to test your hypothesis. The PubMed wordmark and PubMed logo are registered trademarks of the U.S. Department of Health and Human Services (HHS). Categorical variables are any variables where the data represent groups. Types of Variables in Research & Statistics | Examples. What type of data does the variable contain? There are two main types of independent variables. Revised on The presence/absence of the chemical is the independent variable. The other half do not take the vitamins. In statistics, dependent variables are also called: The dependent variable is what you record after youve manipulated the independent variable. Disclaimer. The value of a dependent variable depends on an independent variable, so a variable cannot be both independent and dependent at the same time. 2008;14(1):3-19. doi: 10.1080/08854720802053796. In statistics, dependent variables are also called: Response variables (they respond to a change in another variable) So, they use Photoshop to manipulate the same image of a female by altering the color of her hair: blonde, brunette, red, and brown. The independent variable is usually applied at different levels to see how the outcomes differ. A variable that hides the true effect of another variable in your experiment. You record brain activity with fMRI scans when participants hear infant cries without their awareness. By manipulating the level of an independent variable and observing corresponding changes in a dependent variable, scientists can gain an understanding of many phenomena. If you are having trouble identifying the independent variables of an experiment, there are some questions that may help: Researchers are interested in investigating the effects of the independent variable on other variables, which are known as dependent variables (DV). The .gov means its official. He has trained kindergarten teachers in 8 countries and helped businessmen and women open baby centers and kindergartens in 3 countries. (2022, December 02). Salt tolerance in plants cannot be measured directly, but can be inferred from measurements of plant health in our salt-addition experiment. A researcher wants to determine if the color of an office has any effect on worker productivity. It also makes it easier for other researchers to replicate a study and check for reliability. Performance & security by Cloudflare. To determine the effect that traffic patterns have on the air in a city, employees at the agency perform a study that assesses car usage and air quality in cities around the country. Would you like email updates of new search results? Careers. A sports medicine researcher has been hired by Gatorade to test the effects of its sports drink on athletic performance. Their muscle mass is measured, and only those with a lower level are selected for the study, leaving a total of 80 study participants. In this particular example, the type of information is the independent variable (because it changes), and the amount of information remembered is the dependent variable (because this is being measured). The independent variable (IV) in psychology is the characteristic of an experiment that is manipulated or changed by researchers, not by other variables in the experiment. You have three independent variable levels, and each group gets a different level of treatment. Educators are interested in whether participating in after-school math tutoring can increase scores on standardized math exams. Unauthorized use of these marks is strictly prohibited. If you are having a hard time identifying which variable is the independent variable and which is the dependent variable, remember the dependent variable is the one affected by a change in the independent variable. _________________________________________________________, D.V. Clipboard, Search History, and several other advanced features are temporarily unavailable. Expected to influence the dependent variable, Doesn't change as a result of the experiment, Can be manipulated by researchers in order to study the dependent variable, Expected to be affected by the independent variable, Expected to change as a result of the experiment, Not manipulated by researchers; its changes occur as a result of the independent variable. The researchers identified 120 patients with relatively similar types of cancerous tumors in both size and stage of progression. We could measure blood pressure, or the amount of the stress hormone cortisol in their blood, or by using a paper and pencil measure such as a questionnaire that asks them how much stress they feel. It's what changes as a result of the changes to the independent variable. Here are some tips for identifying each variable type. Independent variables also have different levels. If the independent variable affects the dependent variable, then it should be possible to observe changes in the dependent variable based on the presence or absence of the independent variable. In some experiments, there may only be one level of an IV. (2012). How many minutes or hours of television a person watches is the dependent variable. You think rising sea temperatures might affect the amount of algae in the water.