In an experiment, which variable is manipulated or controlled to observe its effect on the dependent variable?

The independent variable is the one that is manipulated or controlled in an experiment to observe its effect on the dependent variable. This variable is intentionally changed by the researcher to determine if it causes any changes in the outcome being measured, which is the dependent variable. For example, if a researcher is studying the effect of different amounts of sunlight on plant growth, the amount of sunlight is the independent variable that is adjusted.

In an experimental design, identifying the independent variable is crucial because it helps establish a clear cause-and-effect relationship. It allows the researcher to draw conclusions based on how variations in this variable affect the behavior or response of the dependent variable, providing essential insights into the phenomena being studied. Understanding the roles of various types of variables, including independent, dependent, controlled, and confounding variables, is foundational in conducting rigorous scientific research.