An independent variable is the variable that is changed or controlled in a scientific experiment to test the effects on the dependent variable. Show A dependent variable is the variable being tested and measured in a scientific experiment. The dependent variable is 'dependent' on the independent variable. As the experimenter changes the independent variable, the effect on the dependent variable is observed and recorded. Independent vs Dependent Variable
Independent and Dependent Variable ExamplesFor example, a scientist wants to see if the brightness of light has any effect on a moth being attracted to the light. The brightness of the light is controlled by the scientist. This would be the independent variable. How the moth reacts to the different light levels (distance to light source) would be the dependent variable. As another example, say you want to know whether or not eating breakfast affects student test scores. The factor under the experimenter's control is the presence or absence of breakfast, so you know it is the independent variable. The experiment measures test scores of students who ate breakfast versus those who did not. Theoretically, the test results depend on breakfast, so the test results are the dependent variable. Note that test scores are the dependent variable, even if it turns out there is no relationship between scores and breakfast. 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. However, when comparing two different treatments, such as drug A and drug B, it's usual to add another variable, called the control variable. The control variable, which in this case is a placebo that contains the same inactive ingredients as the drugs, makes it possible to tell whether either drug actually affects blood pressure. How to Tell the Variables ApartThe independent and dependent variables may be viewed in terms of cause and effect. If the independent variable is changed, then an effect is seen in the dependent variable. Remember, the values of both variables may change in an experiment and are recorded. The difference is that the value of the independent variable is controlled by the experimenter, while the value of the dependent variable only changes in response to the independent variable. Remembering Variables With DRYMIXWhen results are plotted in graphs, the convention is to use the independent variable as the x-axis and the dependent variable as the y-axis. The DRY MIX acronym can help keep the variables straight: D is the dependent variable M is the manipulated variable or the one that is changed in an experiment Independent vs Dependent Variable Key Takeaways
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Cite this Article Format Your Citation Helmenstine, Todd. "Difference Between Independent and Dependent Variables." ThoughtCo. https://www.thoughtco.com/independent-and-dependent-variables-differences-606115 (accessed December 31, 2022). Is the independent variable affected?The independent variable stands alone. It is not affected or changed by any other variables. That's why it's called independent. If the value of an independent variable is changed, that change happens under the researcher's control—it doesn't happen because of other variables.
What is the affected variable in an experiment called?A dependent variable is what you measure in the experiment and what is affected during the experiment. The dependent variable responds to the independent variable. It is called dependent because it "depends" on the independent variable.
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