Dependent Variable, Independent Variable, Test and Control

When tutoring Biology 12, terms involved in the scientific method need definition.  Let’s look at some.

In an experiment, there is one variable whose value you must wait to see, and (at least) one that you purposely set.  The variable you set is called the independent variable.  The variable you’re curious about is the dependent variable.

A control group – or simply “control” – is one that you leave alone.  You impose changes on the test group by changing the value of the independent variable.  Then, you give the changes time to affect the test group.  Finally, you measure the test group’s dependent variable in order to discover the effect of the changes you imposed.

The typical example to illustrate the roles of these variables is a plant-growing experiment.  If you want to know if using fertilizer accelerates plant growth, your control group will be plants that don’t get fertilizer.  The test group will be plants that do get fertilizer.  The independent variable will be how much fertilizer you give to each plant.  Finally, the dependent variable will be how much each plant grows over the course of the experiment.

There are other terms that relate to the scientific method, but those are generally better documented.  However, we might look at them here in a future post.

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC

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