what is the control variable

A control variable is an experimental element that is constant and unchanged throughout the course of an investigation. It is a variable that is not of interest to the studys objectives but is controlled because it could influence the outcomes. Control variables are held constant or measured throughout a study for both control and experimental groups, while an independent variable varies between control and experimental groups. Control variables can help prevent research biases like omitted variable bias from affecting the results. Any unexpected change in a control variable during an experiment would invalidate the correlation of dependent variables to the independent variable, thus skewing the results and invalidating the working hypothesis. In summary, a control variable is a variable that is held constant in an experiment to assess the relationship between multiple variables.