Final answer:
Control in experimental research maintains internal validity by ensuring that changes in the dependent variable are due to the manipulation of the independent variable. The control group helps eliminate confounding factors, and controlling variables keeps conditions constant across groups. Typically, experiments focus on one dependent variable to simplify results interpretation.
Step-by-step explanation:
Control is crucial in experimental research because it allows for the determination of cause-and-effect relationships by maintaining internal validity. When the only difference between an experimental group and a control group is the independent variable, researchers can infer that any observed changes in the dependent variable are attributable to the independent variable's manipulation. A control group serves to eliminate potential confounding factors, which are variables other than the independent variable that could potentially influence the dependent variable. This group receives either no treatment or a standard treatment.
Control variables, or constants, are also vital as they are the conditions that are kept the same across experimental and control groups to ensure that the observed effect is due to the manipulated variable only. To maintain the internal validity of the experiment, it is recommended to only change one variable at a time, which should be the independent variable. This strategy ensures that any differences seen in outcomes are due to the treatment itself.
Usually, an experiment focuses on one dependent variable to measure the effect of the independent variable. Having multiple dependent variables can complicate the interpretation of results and potentially introduce additional confounding factors. Thus, having a single dependent variable can simplify the analysis and strengthen the experiment’s conclusions regarding causality.