In an experiment, which variable is manipulated by the researcher?

In an experiment, the independent variable is the factor that the researcher deliberately manipulates in order to observe its effects on another variable, known as the dependent variable. This manipulation allows the researcher to establish a cause-and-effect relationship between the two variables. For example, if a researcher wants to see how different amounts of sunlight affect plant growth, the amount of sunlight is the independent variable that they will change, while the growth of the plants is measured as the dependent variable.

The independent variable is critical in experimental design because it helps determine how changes in one factor can lead to changes in another, allowing researchers to test hypotheses and draw conclusions based on their observations. This clear distinction is fundamental to the integrity of experimental research, ensuring that results can be reliably attributed to the manipulation of the independent variable.