# Active Variable

An active variable is a variable that is manipulated by the investigator. It’s designed to shine light on some part of a question or problem, and its usefulness comes in the way it can be controlled by a researcher.

Because of that, an active variable changes in a well-defined and carefully manipulated way over the course of an experiment.

An active variable is the opposite of an attribute or passive variable, which cannot be manipulated.

## Examples of Active Variables.

Consider a research project on the effect of water on greenhouse tomatoes. The amount of water provided to each tomato is an active variable because it is controlled by the investigator. In fact, their manipulation of that variable is the force that drives the experiment.

In an investigation on the responses of middle class families to different types of advertising propaganda, the type of advertising shown for each recorded response is an active variable. The researcher may not be able to manipulate the social status of the family or their predispositions toward advertising, but he can decide which advertisement to test in each instance.

## Experiment Dependence of Active/Attribute Classifications

Since an active variable is defined in terms of manipulation, a variable may be active in certain experiments and not in others.

To understand this, imagine two different studies on children and electronics. The designers of study 1 ask their participants to keep a record of the amount of time their children spend using tablets, computers, and other electronic devices. They also tell participants not to change anything about their daily routine during the course of the study.

The designers of study 2 divide their participants into three groups. They ask group 1 to eliminate electronic use during the course of the study. Group 2  is asked to allow their children devices for 1 hour a day, and group 3 to give unlimited access.

Electronic use is an attribute variable in the first study. In the second, it is a carefully manipulated active variable.

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Statistical concepts explained visually - Includes many concepts such as sample size, hypothesis tests, or logistic regression, explained by Stephanie Glen, founder of StatisticsHowTo.