Variable Examples

A variable is something that can change or that is inconsistent. In mathematical equations, variables are often represented with letters or symbols to show that they are not a fixed number. In research, there are dependent and independent variables.

In an experiment, the independent variable is the variable that is controlled by the researcher. For example, a researcher may control the amount of exercise that he asks participants to perform-30 minutes a day, 1 hour a day, 30 minutes 3 times a week, an hour 3 times a week.

A dependent variable is something that depends on how the researcher manipulates the independent variable. For example, if a researcher is controlling how much exercise participants get, he may be interested in changes to their weight, blood pressure, or body composition. These would be dependent variables.

In simple terms, if the independent variable is manipulated, or changed, then effects will be seen in the dependent variable.

A researcher may control how much sunlight plants are given (independent variable) and then measure the growth of the plants (dependent variable).

A researcher may attempt to control how much a child is read to each day (independent variable) and then measure reading proficiency on standardized tests (dependent variable).

A researcher may control the amount of food given to a dog (independent variable) and the dog's weight gain (dependent variable).

A researcher may control the type of math instruction a student is provided with (independent variable) and then measure the student's math proficiency on standardized tests (dependent variable).

A researcher may control the diet of an athlete (independent variable) and then measure athletic performance on a timed run (dependent variable).

A researcher may control the type of cancer treatment a patient receives (independent variable) and then measure the size of tumors on subsequent scans (dependent variable).