Which variable is measured in an experiment

Apply market research to generate audience insights. Measure content performance. Develop and improve products. List of Partners vendors. Share Flipboard Email. Anne Marie Helmenstine, Ph. Chemistry Expert. Helmenstine holds a Ph. She has taught science courses at the high school, college, and graduate levels. Facebook Facebook Twitter Twitter. Updated January 30, Featured Video. By Dr. Saul McLeod , updated Variables are given a special name that only applies to experimental investigations.

One is called the dependent variable and the other the independent variable. The independent variable is the variable the experimenter manipulates or changes, and is assumed to have a direct effect on the dependent variable. For example, allocating participants to either drug or placebo conditions independent variable in order to measure any changes in the intensity of their anxiety dependent variable.

In a psychology experiment , researchers are looking at how changes in the independent variable cause changes in the dependent variable. Manipulating independent variables and measuring the effect on dependent variables allows researchers to draw conclusions about cause and effect relationships. The dependent variable is dubbed dependent because it is thought to depend in some way on the variations of the independent variable. Experiments can range from simple to quite complicated, so sometimes it can be a bit confusing to learn how to identify the independent and dependent variables.

Here are a few things you can do to help you remember which is which:. If it is something that varies in response to changes in another variable, it is a dependent variable. In many psychology experiments and studies, the dependent variable is a measure of a certain aspect of a participant's behavior. In an experiment looking at how sleep impacts test performance, the dependent variable would test performance because it's a measure of the participants' behavior.

The independent variable is deemed independent because the experimenters are free to vary it as they need. This might mean changing the amount, duration, or type of independent variable that the participants in the study receive as a treatment or condition. One way to help identify the dependent variable is to remember that it depends on the independent variable.

When researchers make changes to the independent variable, they then measure any resulting changes to the dependent variable. How do researchers determine what a good dependent variable will be?

There are a few key features that a scientist might consider:. Stability is often a good sign of a quality dependent variable. If the same experiment is repeated with the same participants, conditions, and experimental manipulations, the effects on the dependent variable should be very close to what they were the first time around. A researcher might also choose dependent variables based on the complexity of their study.

While some studies may only have one dependent variable and one independent variable, it is also possible to have several of each type of variable. Researchers might want to learn how changes in a single independent variable affect several distinct dependent variables. The independent variable is usually applied at different levels to see how the outcome differs. You can apply just two levels e. You can also apply multiple levels e.

Instead, they must find already-existing examples of the independent variable, and investigate how changes in this variable affect the dependent variable.

Instead, you look at a state that raised its minimum wage last year, and compare it to a neighboring state that did not. By comparing the difference in outcomes between the two states and accounting for other factors , you can investigate whether the change in minimum wage had an effect on employment rates. These are known as confounding variables. In types of research where the exact relationship between variables is less certain, you might use different terms for independent and dependent variables.

Sometimes, the variable you think is the cause might not be fully independent — it might be influenced by other variables. In this case, one of these terms is more appropriate:. See an example. Researchers often use charts or graphs to visualize the results of their studies. For instance, how might a graph look from our example study on the impact of a new medication on blood pressure? Frequently asked questions 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.

In an experiment, you manipulate the independent variable and measure the outcome in the dependent variable. For example, in an experiment about the effect of nutrients on crop growth:. Defining your variables, and deciding how you will manipulate and measure them, is an important part of experimental design.