Manipulation Check

Experiments are conducted in communication research in order to determine if manipulating one variable will have an effect on another variable. The variable that is manipulated is called the independent variable. A dependent variable changes based on the manipulation of the independent variable. For example, if a researcher were interested in the effect of violent video games on aggression among young adults, he or she could manipulate the type of violent video game along with the amount of time the participant spent playing these games each week and then measure [Page 901]participant levels of aggression after playing violent video games. In this example, the violent video games would be the independent variable and aggression would be the dependent variable because video game exposure is being manipulated and the level of aggression depends on the amount of exposure to violent video games. One problem the researcher might run into is that participants may not feel that the video games are particularly violent, which is a potential threat to internal validity. Internal validity pertains to the ability of the researcher to conclude that the findings from the study are accurate. In order to overcome this problem, researchers incorporate manipulation checks into their research design. Manipulation checks are a way to help ensure that the independent variable has effectively been manipulated or that the participants understood the independent variable in the way that the researcher planned. This entry discusses the use of manipulation in experimental research. It also explains how to conduct manipulation checks and why it is important to do so.