{"id":306713,"date":"2021-04-02T18:59:38","date_gmt":"2021-04-02T16:59:38","guid":{"rendered":"https:\/\/www.scribbr.nl\/?p=306713"},"modified":"2023-06-22T10:29:40","modified_gmt":"2023-06-22T08:29:40","slug":"extraneous-variables","status":"publish","type":"post","link":"https:\/\/www.scribbr.com\/methodology\/extraneous-variables\/","title":{"rendered":"Extraneous Variables | Examples, Types &#038; Controls"},"content":{"rendered":"<p>In an <a href=https://www.scribbr.com/"https:////www.scribbr.com//methodology//experimental-design///">experiment<\/a>, an <strong>extraneous variable<\/strong> is any variable that you\u2019re not investigating that can potentially affect the outcomes of your research study.<\/p>\n<p><span style=\"font-size: 1rem;\">If left uncontrolled, extraneous variables can lead to inaccurate conclusions about the relationship between<a href=https://www.scribbr.com/"https:////www.scribbr.com//methodology//independent-and-dependent-variables///"> independent and dependent variables<\/a>. They can also introduce a variety of <a href=https://www.scribbr.com/"https:////www.scribbr.com//faq-category//research-bias///">research biases<\/a> to your work, particularly <a href=https://www.scribbr.com/"https:////www.scribbr.com//research-bias//selection-bias///">selection bias<\/a><\/span><\/p>\n<table class=\"kb-table responsive-inline full-width auto-th\">\n<thead>\n<tr>\n<th>Research question<\/th>\n<th>Extraneous variables<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<th>Is memory capacity related to test performance?<\/th>\n<td>\n<ul>\n<li aria-level=\"1\">Test-taking time of day<\/li>\n<li aria-level=\"1\">Test anxiety<\/li>\n<li aria-level=\"1\">Level of stress<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<tr>\n<th>Does sleep deprivation affect driving ability?<\/th>\n<td>\n<ul>\n<li aria-level=\"1\">Road conditions<\/li>\n<li aria-level=\"1\">Years of driving experience<\/li>\n<li aria-level=\"1\">Noise<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<tr>\n<th>Does light exposure improve learning ability in mice?<\/th>\n<td>\n<ul>\n<li aria-level=\"1\">Type of mouse<\/li>\n<li aria-level=\"1\">Genetic background<\/li>\n<li aria-level=\"1\">Learning environment<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p><!--more--><\/p>\n<h2>Why do extraneous variables matter?<\/h2>\n<p>Extraneous variables can threaten the <a href=https://www.scribbr.com/"https:////www.scribbr.com//methodology//internal-validity///">internal validity<\/a> of your study by providing alternative explanations for your results.<\/p>\n<p>When not accounted for, this <a href=https://www.scribbr.com/"https:////www.scribbr.com//methodology//types-of-variables///">type of variable<\/a> can also introduce many biases to your research, particularly types of selection bias such as:<\/p>\n<ul>\n<li aria-level=\"1\"><strong><a href=https://www.scribbr.com/"https:////www.scribbr.com//research-bias//sampling-bias///">Sampling bias<\/a> or <a href=https://www.scribbr.com/"https:////www.scribbr.com//research-bias//ascertainment-bias///">ascertainment bias<\/a><\/strong>: when some members of the intended population are less likely to be included than others.<\/li>\n<\/ul>\n<ul>\n<li aria-level=\"1\"><a href=https://www.scribbr.com/"https:////www.scribbr.com//research-bias//attrition-bias///"><strong>Attrition bias<\/strong><\/a>: when participants who drop out of a study are <a href=https://www.scribbr.com/"https:////www.scribbr.com//methodology//random-vs-systematic-error///">systematically <\/a>different from those who stay.<\/li>\n<\/ul>\n<ul>\n<li aria-level=\"1\"><a href=https://www.scribbr.com/"https:////www.scribbr.com//research-bias//survivorship-bias///"><strong>Survivorship bias <\/strong><\/a>: when researchers draw conclusions by only focusing on examples of successful individuals (the \u201csurvivors\u201d) rather than the group as a whole.<\/li>\n<\/ul>\n<ul>\n<li aria-level=\"1\"><strong><a href=https://www.scribbr.com/"https:////www.scribbr.com//research-bias//nonresponse-bias///">Nonresponse bias<\/a><\/strong>: when people who don\u2019t respond to a survey are different in significant ways from those who do.<\/li>\n<\/ul>\n<ul>\n<li aria-level=\"1\"><strong><a href=https://www.scribbr.com/"https:////www.scribbr.com//research-bias//undercoverage-bias///">Undercoverage bias<\/a><\/strong>: when some members of your population are not represented in the sample.<\/li>\n<\/ul>\n<p>In an <a href=https://www.scribbr.com/"https:////www.scribbr.com//methodology//experimental-design///">experiment<\/a>, you manipulate an <a href=https://www.scribbr.com/"https:////www.scribbr.com//methodology//independent-and-dependent-variables///">independent variable<\/a> to study its effects on a dependent variable.<\/p>\n<figure class=\"kb-textbox border-left green\"><figcaption>Example: Experimental study<\/figcaption>In a study on mental performance, you test whether wearing a white lab coat, your independent variable, improves scientific reasoning, your dependent variable.<\/p>\n<p>You recruit students from a university to participate in the study. You manipulate the independent variable by splitting participants into two groups:<\/p>\n<ul>\n<li aria-level=\"1\">Participants in the <strong>experimental group<\/strong> are asked to wear a lab coat during the study.<\/li>\n<li aria-level=\"1\">Participants in the <a href=https://www.scribbr.com/"https:////www.scribbr.com//methodology//control-group///"><strong>control group<\/strong><\/a> are asked to wear a casual coat during the study.<\/li>\n<\/ul>\n<p>All participants are given a scientific knowledge quiz, and their scores are compared between groups.<\/figure>\n<p>When extraneous variables are uncontrolled, it\u2019s hard to determine the exact <a href=https://www.scribbr.com/"https:////www.scribbr.com//commonly-confused-words//affect-vs-effect///">effects<\/a> of the independent variable on the dependent variable, because the effects of extraneous variables may mask them.<\/p>\n<p>Uncontrolled extraneous variables can also make it seem as though there is a true effect of the independent variable in an experiment when there\u2019s actually none.<\/p>\n<figure class=\"kb-textbox border-left green\"><figcaption>Example: Extraneous variables<\/figcaption>In your experiment, these extraneous variables can affect the science knowledge scores:<\/p>\n<ul>\n<li aria-level=\"1\">Participant\u2019s major (e.g., STEM or humanities)<\/li>\n<li aria-level=\"1\">Participant\u2019s interest in science<\/li>\n<li aria-level=\"1\">Demographic variables such as gender or educational background<\/li>\n<li aria-level=\"1\">Time of day of testing<\/li>\n<li aria-level=\"1\">Experiment environment or setting<\/li>\n<\/ul>\n<p>If these variables systematically differ between the groups, you can\u2019t be sure whether your results come from your independent variable manipulation or from the extraneous variables.<\/figure>\n<p>Controlling extraneous variables is an important aspect of <a href=https://www.scribbr.com/"https:////www.scribbr.com//methodology//experimental-design///">experimental design<\/a>. When you control an extraneous variable, you turn it into a <a href=https://www.scribbr.com/"https:////www.scribbr.com//methodology//control-variable///">control variable<\/a>.<\/p>\n<h2>Extraneous vs. confounding variables<\/h2>\n<p>A <a href=https://www.scribbr.com/"https:////www.scribbr.com//methodology//confounding-variables///"><strong>confounding variable<\/strong><\/a> is a type of extraneous variable that is associated with both the independent and dependent variables.<\/p>\n<ul>\n<li aria-level=\"1\">An extraneous variable is anything that could influence the dependent variable.<\/li>\n<li aria-level=\"1\">A confounding variable influences the dependent variable, and <strong>also<\/strong> correlates with or <a href=https://www.scribbr.com/"https:////www.scribbr.com//methodology//correlation-vs-causation///">causally<\/a> affects the independent variable.<\/li>\n<\/ul>\n<p>In a <a href=https://www.scribbr.com/"https:////www.scribbr.com//methodology//conceptual-framework///">conceptual framework<\/a> diagram, you can draw an arrow from a confounder to the independent variable as well as to the dependent variable. You can draw an arrow from extraneous variables to a dependent variable.<\/p>\n<p><img decoding=\"async\" src=https://www.scribbr.com/"https:////www.scribbr.com//wp-content//uploads//2021//04//extraneous-variables.png/" alt=\"Extraneous vs confounding variables\" width=\"660px\" class=\"aligncenter size-full wp-image-306715 mt-5 mb-5\" srcset=\"https:\/\/www.scribbr.com\/wp-content\/uploads\/2021\/04\/extraneous-variables.png 512w, https:\/\/www.scribbr.com\/wp-content\/uploads\/2021\/04\/extraneous-variables-300x171.png 300w\" sizes=\"(max-width: 512px) 100vw, 512px\" \/><\/p>\n<figure class=\"kb-textbox border-left green\"><figcaption>Example: Confounding vs. extraneous variables<\/figcaption>Having participants who work in scientific professions (in labs) is a confounding variable in your study, because this type of work correlates with wearing a lab coat and better scientific reasoning.<\/p>\n<p>People who work in labs would regularly wear lab coats and may have higher scientific knowledge in general. Therefore, it\u2019s unlikely that your manipulation will increase scientific reasoning abilities for these participants.<\/p>\n<p>Variables that only impact on scientific reasoning are extraneous variables. These include participants\u2019 interests in science and undergraduate majors. While interest in science may affect scientific reasoning ability, it\u2019s not necessarily related to wearing a lab coat.<\/p>\n<p><img decoding=\"async\" src=https://www.scribbr.com/"https:////www.scribbr.com//wp-content//uploads//2021//04//extraneous-variables-example.png/" alt=\"Example of extraneous vs confounding variables\" width=\"660px\" class=\"wp-image-306728 aligncenter mt-5 mb-5\" srcset=\"https:\/\/www.scribbr.com\/wp-content\/uploads\/2021\/04\/extraneous-variables-example.png 637w, https:\/\/www.scribbr.com\/wp-content\/uploads\/2021\/04\/extraneous-variables-example-300x167.png 300w\" sizes=\"(max-width: 637px) 100vw, 637px\" \/><\/figure>\n<h2>Types and controls of extraneous variables<\/h2>\n<h3>Demand characteristics<\/h3>\n<p><a href=https://www.scribbr.com/"https:////www.scribbr.com//research-bias//demand-characteristics///">Demand characteristics<\/a> are cues that encourage participants to conform to researchers\u2019 behavioral expectations.<\/p>\n<p>Sometimes, participants can <a href=https://www.scribbr.com/"https:////www.scribbr.com//commonly-confused-words//infer-vs-imply//#infer\">infer<\/a> the intentions behind a research study from the materials or experimental settings, and use these hints to act in ways that are consistent with study hypotheses. These demand characteristics can <a href=https://www.scribbr.com/"https:////www.scribbr.com//faq-category//research-bias///">bias<\/a> the study outcomes and reduce the <a href=https://www.scribbr.com/"https:////www.scribbr.com//methodology//external-validity///">external validity<\/a>, or <a href=https://www.scribbr.com/"https:////www.scribbr.com//research-bias//generalizability///">generalizability<\/a>, of the results.<\/p>\n<figure class=\"kb-textbox border-left green\"><figcaption>Example: Demand characteristics<\/figcaption>Research participants in the experimental group easily draw links between the lab setting, being asked to wear lab coats, and the questions on their scientific knowledge.<\/p>\n<p>They work harder to do well on the quiz by paying more attention to the questions.<\/figure>\n<p>You can avoid demand characteristics by making it difficult for participants to guess the aim of your study. Ask participants to perform unrelated filler tasks or fill out plausibly relevant surveys to lead them away from the true nature of the study.<\/p>\n<h3>Experimenter effects<\/h3>\n<p>Experimenter effects are unintentional actions by researchers that can influence study outcomes.<\/p>\n<p><a href=https://www.scribbr.com/"https:////www.scribbr.com//commonly-confused-words//there-their-theyre///">There<\/a> are two main types of experimenter effects:<\/p>\n<ul>\n<li aria-level=\"1\">Experimenters\u2019 interactions with participants can unintentionally affect their behaviours.<\/li>\n<li aria-level=\"1\">Errors in measurement, observation, analysis, or interpretation may change the study results.<\/li>\n<\/ul>\n<figure class=\"kb-textbox border-left green\"><figcaption>Example: Experimenter effect<\/figcaption>You motivate and encourage the participants wearing the lab coats to do their best on the quiz. They are more comfortable in the lab environment and feel confident going into the quiz; therefore, they perform well.<\/p>\n<p>Participants wearing the non-lab coats are not encouraged to perform well on the quiz. Therefore, they don\u2019t work as hard on their responses.<\/figure>\n<p>To avoid experimenter effects, you can implement <a href=https://www.scribbr.com/"https:////www.scribbr.com//methodology//double-blind-study///">masking (blinding)<\/a> to hide the condition assignment from participants and experimenters. In a double-blind study, researchers won\u2019t be able to bias participants towards acting in expected ways or selectively interpret results to suit their <a href=https://www.scribbr.com/"https:////www.scribbr.com//statistics//hypothesis-testing///">hypotheses<\/a>.<\/p>\n<h3>Situational variables<\/h3>\n<p>Situational variables, such as lighting or temperature, can alter participants\u2019 behaviors in study environments. These factors are sources of <a href=https://www.scribbr.com/"https:////www.scribbr.com//methodology//random-vs-systematic-error///">random error<\/a> or random variation in your measurements.<\/p>\n<p>To understand the true relationship between independent and dependent variables, you\u2019ll need to reduce or eliminate the effect of situational factors on your study outcomes.<\/p>\n<figure class=\"kb-textbox border-left green\"><figcaption>Example: Situational variable<\/figcaption>To perform your experiment, you use the lab rooms on campus. They are only available either early in the morning or late in the day. Because time of day may affect test performance, it\u2019s an extraneous variable.<\/figure>\n<p>To avoid situational variables from influencing study outcomes, it\u2019s best to hold variables constant throughout the study or statistically account for them in your analyses.<\/p>\n<h3>Participant variables<\/h3>\n<p>A participant variable is any characteristic or aspect of a participant\u2019s background that could affect study results, even though it&#8217;s not the focus of an experiment.<\/p>\n<p>Participant variables can include sex, gender identity, age, educational attainment, marital status, religious affiliation, etc.<\/p>\n<p>Since these individual differences between participants may lead to different outcomes, it\u2019s important to measure and analyze these variables.<\/p>\n<figure class=\"kb-textbox border-left green\"><figcaption>Example: Participant variables<\/figcaption>Educational background and undergraduate majors are important participant variables for your study on scientific reasoning. Participants with strong educational backgrounds in STEM subjects are likely to perform better than others.<\/figure>\n<p>To control participant variables, you should aim to use <a href=https://www.scribbr.com/"https:////www.scribbr.com//methodology//random-assignment///">random assignment<\/a> to divide your <a href=https://www.scribbr.com/"https:////www.scribbr.com//methodology//population-vs-sample///">sample<\/a> into control and experimental groups. Random assignment makes your groups comparable by evenly distributing participant characteristics between them.<\/p>\n<h2 id=\"other\">Other interesting articles<\/h2>\n<p data-pm-slice=\"1 1 []\">If you want to know more about <a href=https://www.scribbr.com/"https:////www.scribbr.com//category//statistics///" class=\"ProsemirrorEditor-link\">statistics<\/a>, <a href=https://www.scribbr.com/"https:////www.scribbr.com//category//methodology///" class=\"ProsemirrorEditor-link\">methodology<\/a>, or <a href=https://www.scribbr.com/"https:////www.scribbr.com//faq-category//research-bias///" class=\"ProsemirrorEditor-link\">research bias<\/a>, make sure to check out some of our other articles with explanations and examples.<\/p>\n<div class=\"container\">\n<div class=\"row\">\n<div class=\"col-md\" style=\"background-color: #e8f2fc; padding: 1.27rem 1.56rem; line-height: 1.8; border-radius: .5rem; margin-right: 0.5rem; margin-top: 0.5rem;\">\n<p><strong><em class=\"fa fa-bar-chart\" aria-hidden=\"true\"><\/em>Statistics<\/strong><\/p>\n<ul style=\"padding: 5px;\">\n<li><a href=https://www.scribbr.com/"https:////www.scribbr.com//statistics//normal-distribution///">Normal distribution<\/a><\/li>\n<li><a href=https://www.scribbr.com/"https:////www.scribbr.com//statistics//skewness///">Skewness<\/a><\/li>\n<li><a href=https://www.scribbr.com/"https:////www.scribbr.com//statistics//kurtosis///">Kurtosis<\/a><\/li>\n<li><a href=https://www.scribbr.com/"https:////www.scribbr.com//statistics//degrees-of-freedom///">Degrees of freedom<\/a><\/li>\n<li><a href=https://www.scribbr.com/"https:////www.scribbr.com//statistics//variance///">Variance<\/a><\/li>\n<li><a href=https://www.scribbr.com/"https:////www.scribbr.com//statistics//null-and-alternative-hypotheses///">Null hypothesis<\/a><\/li>\n<\/ul>\n<\/div>\n<div class=\"col-md\" style=\"background-color: #e8f2fc; padding: 1.27rem 1.56rem; line-height: 1.8; border-radius: .5rem; margin-right: 0.5rem; margin-top: 0.5rem;\">\n<p><strong><em class=\"fa fa-list-ul\" aria-hidden=\"true\"><\/em> Methodology<\/strong><\/p>\n<ul style=\"padding: 5px;\">\n<li><a href=https://www.scribbr.com/"https:////www.scribbr.com//methodology//discourse-analysis///">Discourse analysis<\/a><\/li>\n<li><a href=https://www.scribbr.com/"https:////www.scribbr.com//methodology//control-group///">Control groups<\/a><\/li>\n<li><a href=https://www.scribbr.com/"https:////www.scribbr.com//methodology//mixed-methods-research///">Mixed methods research<\/a><\/li>\n<li><a href=https://www.scribbr.com/"https:////www.scribbr.com//methodology//non-probability-sampling///">Non-probability sampling<\/a><\/li>\n<li><a href=https://www.scribbr.com/"https:////www.scribbr.com//methodology//quantitative-research///">Quantitative research<\/a><\/li>\n<li><a href=https://www.scribbr.com/"https:////www.scribbr.com//methodology//ecological-validity///">Ecological validity<\/a><\/li>\n<\/ul>\n<\/div>\n<div class=\"col-md\" style=\"background-color: #e8f2fc; padding: 1.27rem 1.56rem; line-height: 1.8; border-radius: .5rem; margin-right: 0.5rem; margin-top: 0.5rem;\">\n<p><strong><em class=\"fa fa-globe\" aria-hidden=\"true\"><\/em> Research bias<\/strong><\/p>\n<ul style=\"padding: 5px;\">\n<li><a href=https://www.scribbr.com/"https:////www.scribbr.com//research-bias//pygmalion-effect///">Rosenthal effect<\/a><\/li>\n<li><a href=https://www.scribbr.com/"https:////www.scribbr.com//research-bias//implicit-bias///">Implicit bias<\/a><\/li>\n<li><a href=https://www.scribbr.com/"https:////www.scribbr.com//research-bias//cognitive-bias///">Cognitive bias<\/a><\/li>\n<li><a href=https://www.scribbr.com/"https:////www.scribbr.com//research-bias//selection-bias///">Selection bias<\/a><\/li>\n<li><a href=https://www.scribbr.com/"https:////www.scribbr.com//research-bias//negativity-bias///">Negativity bias<\/a><\/li>\n<li><a href=https://www.scribbr.com/"https:////www.scribbr.com//research-bias//status-quo-bias///">Status quo bias<\/a><\/li>\n<\/ul>\n<\/div>\n<\/div>\n<\/div>\n    <h2>Frequently asked questions about extraneous variables<\/h2>\n<dl class=\"faq-list faq-list--arrows w-100 my-5\" itemscope itemtype=\"https:\/\/schema.org\/FAQPage\">\n            <div itemscope itemprop=\"mainEntity\" itemtype=\"https:\/\/schema.org\/Question\">\n            <dt id=\"extraneous-vs-confounding-variables\" class=\"faq-list__title\">\n                <a href=https://www.scribbr.com/"https:////www.scribbr.com//frequently-asked-questions//extraneous-vs-confounding-variables///" class=\"faq-list__link qa-faq-anchor\">\n                    <span itemprop=\"name\">\n                        What\u2019s the difference between extraneous and confounding variables?\n                    <\/span>\n                <\/a>\n            <\/dt>\n            <dd id=\"extraneous-vs-confounding-variables-answer\" class=\"faq-list__answer qa-faq-answer kb-article-styles\" itemscope itemprop=\"acceptedAnswer\" itemtype=\"https:\/\/schema.org\/Answer\">\n                <div itemprop=\"text\">\n                                        <p>An <a href=https://www.scribbr.com/"https:////www.scribbr.com//methodology//extraneous-variables///"><strong>extraneous variable<\/strong> <\/a>is any variable that you\u2019re not investigating that can potentially affect the <a href=https://www.scribbr.com/"https:////www.scribbr.com//methodology//independent-and-dependent-variables///">dependent variable<\/a> of your research study.<\/p>\n<p>A <a href=https://www.scribbr.com/"https:////www.scribbr.com//methodology//confounding-variables///"><strong>confounding variable<\/strong><\/a> is a type of extraneous variable that not only affects the dependent variable, but is also related to the independent variable.<\/p>\n\n                <\/div>\n            <\/dd>\n        <\/div>\n            <div itemscope itemprop=\"mainEntity\" itemtype=\"https:\/\/schema.org\/Question\">\n            <dt id=\"types-of-extraneous-variables\" class=\"faq-list__title\">\n                <a href=https://www.scribbr.com/"https:////www.scribbr.com//frequently-asked-questions//types-of-extraneous-variables///" class=\"faq-list__link qa-faq-anchor\">\n                    <span itemprop=\"name\">\n                        What are the types of extraneous variables?\n                    <\/span>\n                <\/a>\n            <\/dt>\n            <dd id=\"types-of-extraneous-variables-answer\" class=\"faq-list__answer qa-faq-answer kb-article-styles\" itemscope itemprop=\"acceptedAnswer\" itemtype=\"https:\/\/schema.org\/Answer\">\n                <div itemprop=\"text\">\n                                        <p>There are 4 main types of <a href=https://www.scribbr.com/"https:////www.scribbr.com//methodology//extraneous-variables///">extraneous variables<\/a>:<\/p>\n<ul>\n<li><a href=https://www.scribbr.com/"https:////www.scribbr.com//research-bias//demand-characteristics///"><strong>Demand characteristics<\/strong><\/a>: environmental cues that encourage participants to conform to researchers\u2019 expectations.<\/li>\n<li><strong>Experimenter effects<\/strong>: unintentional actions by researchers that influence study outcomes.<\/li>\n<li><strong>Situational variables<\/strong>: environmental variables that alter participants\u2019 behaviors.<\/li>\n<li><strong>Participant variables<\/strong>: any characteristic or aspect of a participant\u2019s background that could affect study results.<\/li>\n<\/ul>\n\n                <\/div>\n            <\/dd>\n        <\/div>\n            <div itemscope itemprop=\"mainEntity\" itemtype=\"https:\/\/schema.org\/Question\">\n            <dt id=\"why-are-control-variables-important\" class=\"faq-list__title\">\n                <a href=https://www.scribbr.com/"https:////www.scribbr.com//frequently-asked-questions//why-are-control-variables-important///" class=\"faq-list__link qa-faq-anchor\">\n                    <span itemprop=\"name\">\n                        Why are control variables important?\n                    <\/span>\n                <\/a>\n            <\/dt>\n            <dd id=\"why-are-control-variables-important-answer\" class=\"faq-list__answer qa-faq-answer kb-article-styles\" itemscope itemprop=\"acceptedAnswer\" itemtype=\"https:\/\/schema.org\/Answer\">\n                <div itemprop=\"text\">\n                                        <p><a href=https://www.scribbr.com/"https:////www.scribbr.com//methodology//control-variable///">Control variables<\/a> help you establish a correlational or causal relationship between variables by enhancing <a href=https://www.scribbr.com/"https:////www.scribbr.com//methodology//internal-validity///">internal validity<\/a>.<\/p>\n<p>If you don\u2019t control relevant <a href=https://www.scribbr.com/"https:////www.scribbr.com//methodology//extraneous-variables///">extraneous variables<\/a>, they may influence the outcomes of your study, and you may not be able to demonstrate that your results are really an effect of your <a href=https://www.scribbr.com/"https:////www.scribbr.com//methodology//independent-and-dependent-variables///">independent variable<\/a>.<\/p>\n\n                <\/div>\n            <\/dd>\n        <\/div>\n            <div itemscope itemprop=\"mainEntity\" itemtype=\"https:\/\/schema.org\/Question\">\n            <dt id=\"what-does-controlling-for-a-variable-mean\" class=\"faq-list__title\">\n                <a href=https://www.scribbr.com/"https:////www.scribbr.com//frequently-asked-questions//what-does-controlling-for-a-variable-mean///" class=\"faq-list__link qa-faq-anchor\">\n                    <span itemprop=\"name\">\n                        What does \u201ccontrolling for a variable\u201d mean?\n                    <\/span>\n                <\/a>\n            <\/dt>\n            <dd id=\"what-does-controlling-for-a-variable-mean-answer\" class=\"faq-list__answer qa-faq-answer kb-article-styles\" itemscope itemprop=\"acceptedAnswer\" itemtype=\"https:\/\/schema.org\/Answer\">\n                <div itemprop=\"text\">\n                                        <p>\u201cControlling for a variable\u201d means measuring <a href=https://www.scribbr.com/"https:////www.scribbr.com//methodology//extraneous-variables///">extraneous variables<\/a> and accounting for them statistically to remove their effects on other variables.<\/p>\n<p>Researchers often model <a href=https://www.scribbr.com/"//?p=303804\%22>control variable<\/a> data along with <a href=https://www.scribbr.com/"https:////www.scribbr.com//methodology//independent-and-dependent-variables///">independent and dependent variable<\/a> data in <a href=https://www.scribbr.com/"https:////www.scribbr.com//statistics//multiple-linear-regression///">regression analyses<\/a> and <a href=https://www.scribbr.com/"https:////www.scribbr.com//statistics//two-way-anova///">ANCOVAs<\/a>. That way, you can isolate the control variable\u2019s effects from the relationship between the variables of interest.<\/p>\n\n                <\/div>\n            <\/dd>\n        <\/div>\n    <\/dl>\n","protected":false},"excerpt":{"rendered":"<p>In an experiment, an extraneous variable is any variable that you\u2019re not investigating that can potentially affect the outcomes of your research study. If left uncontrolled, extraneous variables can lead to inaccurate conclusions about the relationship between independent and dependent variables. They can also introduce a variety of research biases to your work, particularly selection [&hellip;]<\/p>\n","protected":false},"author":115,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_relevanssi_hide_post":"","_relevanssi_hide_content":"","_relevanssi_pin_for_all":"","_relevanssi_pin_keywords":"","_relevanssi_unpin_keywords":"","_relevanssi_related_keywords":"","_relevanssi_related_include_ids":"","_relevanssi_related_exclude_ids":"","_relevanssi_related_no_append":"","_relevanssi_related_not_related":"","_relevanssi_related_posts":"","_relevanssi_noindex_reason":""},"categories":[23650],"tags":[],"acf":[],"yoast_head":"<title>Extraneous Variables | Examples, Types &amp; Controls<\/title>\n<!-- Added by HTTrack --><meta http-equiv="content-type" content="text/html;charset=UTF-8" /><!-- /Added by HTTrack -->
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