Research Variables 101: Dependent, Independent, Control Variables & More (With Examples)

Do the types of variables in research all blur together? Here's how to tell the six apart and use each correctly. 🎓 GET 1-ON-1 RESEARCH METHODOLOGY HELP: https://go.gradcoach.com/B4QRU 🧰 FREE RESEARCH TOOLKIT: https://go.gradcoach.com/duwDD THE KEY QUESTIONS WE ANSWER IN THIS VIDEO What is a variable in research? Any attribute that can change or vary over time, which is where the name comes from. A medicine's dosage is a variable because the amount can vary. Age, gender and ethnicity are demographic variables, because people differ in each. Variables are mostly the focus of quantitative studies, where the interest is usually in how one variable affects another and by how much. They're also what a hypothesis is built on. Six types come up: independent, dependent, control, moderating, mediating and confounding. What are independent and dependent variables? The independent variable is the cause and the dependent variable is the effect, or at least the thing the effect happens to. When the independent variable increases or decreases, the dependent variable changes in response. Increase a medication's dosage and health outcomes shift. Change a teaching method and standardized test scores move. Watch for the other names: independent variables are also called explanatory or predictive variables, and dependent variables are called response or outcome variables. What is a control variable? Any variable a researcher deliberately holds constant so it can't influence the others. Isolating the variable you care about is one of the hardest parts of establishing causation, so researchers fix everything else they can: temperature, time of day, lighting. Control variables alone won't prove causation, though. That needs an experimental design with near-complete control over the environment and the variables, and even then causality is never simple. What is a moderating variable? A variable that changes the strength or direction of the relationship between an independent and a dependent variable. In a study of how sleep deprivation affects cognitive performance, age could moderate it: younger people might be less affected by lost sleep than older people, or the reverse. Sex or other physical attributes could do the same. Moderators don't cause outcomes, they modify relationships that already exist, so two similar groups moderated differently can get very different results from the same experiment. What is a mediating variable? The in-betweener in a chain of cause and effect, used to explain why an independent variable affects a dependent one. Researching the impact of education level on income, job skills could be the mediator: higher education may lead to higher income, but it's the skills gained along the way that qualify someone for better-paying work. Put formally, if variable one affects variable two, which affects variable three, two is the mediator. What is a confounding variable? An unmeasured outside factor, also called a third variable or a lurking variable, that affects the relationship between the two you're studying. The damage it does is specific: it makes two variables look causally linked when they aren't. Studying whether sleep affects college students' academic performance, stress could be confounding it. If stressed students sleep less, and stress also hurts performance, leaving stress untracked makes sleep look like the direct cause. Think hard about what else could be moving your variables, then control for it. OVERVIEW 00:00 Introduction 01:05 What a variable is 01:36 Why variables matter in quantitative research 01:56 How variables underpin a hypothesis 02:33 The big three variables 02:41 Independent and dependent variables 03:28 Other names you'll see for these two 04:27 What a control variable does 05:18 Why control variables alone can't prove causation 06:10 Moderating variables explained 07:28 Mediating variables explained 08:19 Confounding variables explained 09:00 A confounding example: sleep, stress and grades 10:04 Recap of the six types FREE RESOURCES What (Exactly) Are Research Variables? - https://go.gradcoach.com/oFq5n Research Design For Quantitative Studies -    • QUANTITATIVE Research Design: Everything Y...   What (Exactly) Is Research Design? - https://go.gradcoach.com/5hzJT What Is a Research Hypothesis? - https://go.gradcoach.com/WGh2b Quantitative Data Analysis 101 - https://go.gradcoach.com/wanrV Methodology Template - https://go.gradcoach.com/WUrpp PREMIUM RESOURCES Research Methodology 101 (Blueprint) - https://go.gradcoach.com/RnqbV OUR SOCIALS 🟢 Facebook -   / gradcoachofficial   🟢 Twitter -   / gradcoachdotcom   🟢 LinkedIn -   / grad-coach-intl   🟢 YouTube -    / gradcoach