In an experiment, what is the independent variable?

The independent variable in an experiment is the variable that is manipulated by the experimenter to observe its effect on other variables, typically the dependent variable. This manipulation allows researchers to determine cause-and-effect relationships. By changing this variable, the experimenter can see how it influences the outcome, providing insights into the dynamics of the relationship being studied.

Each of the other options describes different components or aspects of an experiment. The outcome being measured corresponds to the dependent variable, which is affected by changes in the independent variable. A factor that influences results could refer to either independent or confounding variables but does not specifically identify the one being manipulated. Conditions kept constant during the experiment are referred to as controlled variables, which help eliminate alternative explanations for the results by ensuring that any changes in the dependent variable can be attributed to the manipulation of the independent variable. Thus, identifying the independent variable as the manipulated factor is key to understanding the experimental setup.