How can you tell if a research study has a confounding vs extraneous variable?
What is a Confounding Variable?By Julia Simkus, published Jan 24, 2022 Show A confounding variable is an unmeasured third variable that influences, or “confounds,” the relationship between an independent and a dependent variable by suggesting the presence of a spurious correlation. Due to the presence of confounding variables in research, we should never assume that a correlation between two variables implies a causation. When an extraneous variable has not been properly controlled and interferes with the dependent variable (i.e. results) it is called a confounding variable. For example, if there is an association between an independent variable (IV) and a dependent variable (DV), but that association is due to the fact that the two variables are both affected by a third variable (C), then the association between the IV and DV is extraneous. Variable C would be considered the confounding variable in this example. We would say that the IV and DV are confounded by C whenever C causally influences both the IV and the DV. In order to accurately estimate the effect of the IV on the DV, the researcher must reduce the effects of C. If you identify a causal relationship between the independent variable and the dependent variable, that relationship might not actually exist because it could be affected by the presence of a confounding variable. Even if the cause and effect relationship does exist, the confounding variable still might overestimate or underestimate the impact of the independent variable on the dependent variable. How to reduce the impact of confounding variablesIt is important to identify all possible confounding variables and consider the impact of them in your research design in order to ensure the internal validity of your results. Here are some techniques to reduce the effects of these confounding variables:
ExampleSuppose we wanted to measure the effects of caloric intake (IV) on weight (DV). We would have to try to ensure that confounding variables did not affect the results. These variables could include:
Frequently asked questions about confounding variables1. What is the difference between an extraneous variable and a confounding variable? A confounding variable is a type of extraneous variable. Confounding variables affect both the independent and dependent variables. They influence the dependent variable directly and either correlate with or causally affect the independent variable. An extraneous variable is any variable that you are not investigating that can influence the dependent variable. 2. What is Confounding Bias? Confounding bias is bias that is the result of having confounding variables in your study design. If the observed association overestimates the effect of the independent variable on the dependent variable, this is known as positive confounding bias. If the observed association underestimates the effect of the independent variable on the dependent variable, this is known as negative confounding bias. About the AuthorJulia Simkus is an undergraduate student at Princeton University, majoring in Psychology. She plans to pursue a PhD in Clinical Psychology upon graduation from Princeton in 2023. Julia has co-authored two journal articles, one titled “Substance Use Disorders and Behavioral Addictions During the COVID-19 Pandemic and COVID-19-Related Restrictions," which was published in Frontiers in Psychiatry in April 2021 and the other titled “Food Addiction: Latest Insights on the Clinical Implications," to be published in Handbook of Substance Misuse and Addictions: From Biology to Public Health in early 2022. How to reference this article:How to reference this article:Simkus, J. (2022, Jan 24). What is a Confounding Variable? Simply Psychology. www.simplypsychology.org/confounding-variable.html SourcesGlen, Stephanie. Confounding Variable: Simple Definition and Example. Retrieved from StatisticsHowTo.com: Elementary Statistics for the rest of us! https://www.statisticshowto.com/experimental-design/confounding-variable/ Thomas, L. (2021). Understanding confounding variables. Scribbr. Retrieved from https://www.scribbr.com/methodology/confounding-variables/ University of Michigan. (n.d.). Confounding Variables. ICPSR. Retrieved from https://www.icpsr.umich.edu/web/pages/instructors/setups2012/exercises/notes/confounding-variable.html Home | About Us | Privacy Policy | Advertise | Contact Us Simply Psychology's content is for informational and educational purposes only. Our website is not intended to be a substitute for professional medical advice, diagnosis, or treatment. © Simply Scholar Ltd - All rights reserved
What is example of extraneous and confounding variables?In simple words, People wearing lab coats (independent variables) and having scientific skills (dependent variable) are both confounding variables. While scientific skills (dependent variable) and having interest in science is an extraneous variable.
Are all extraneous variables confounding?Not all extraneous variables will alter research results, but they become a confounding variable when they do. A confounding variable is some external factor related to the independent variable and directly changes the dependent variable in a way that impacts study results.
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