Which type of variable is manipulated or changed in an experiment to observe its effect?

In scientific experiments, the type of variable that is manipulated or changed by the researcher is referred to as the independent variable. This variable is the one that is intentionally altered to observe its effects on other variables, particularly the dependent variable, which is measured to see how it responds to changes in the independent variable.

For instance, if a scientist is testing the effect of different amounts of sunlight on plant growth, the amount of sunlight is the independent variable because it is what is being changed or controlled in the experiment. The growth of the plants, measured in terms of height or biomass, would be the dependent variable, as it depends on the sunlight levels.

Other types of variables mentioned are important for different reasons. Controlled variables are those that are kept constant to ensure that any changes in the dependent variable can be attributed more confidently to the independent variable. Confounding variables, on the other hand, are those that might unintentionally influence the outcome of the experiment and can lead to misleading results if not properly controlled. Understanding these distinctions is essential for designing sound experiments and interpreting their results accurately.