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Variables, Control
Control variables are the variables (i.e., factors, elements) that researchers seek to keep constant when conducting research. In a typical research design, a researcher measures the effect an independent variable has on a dependent variable. To properly measure the relationship between a dependent variable and an independent variable, other variables, known as extraneous or confounding variables, must be controlled (i.e., neutralized, eliminated, standardized).
Although control variables are not the central interest of a researcher, they are paramount to properly understand the relationship between independent and dependent variables. If extraneous variables are not controlled in a research project, they can skew the results of a study. If used properly, control variables can help the researcher accurately test the value of an independent variable on a dependent variable. Therefore, controlling extraneous variables is an important objective of research design.
Control variables are often overlooked in research design, which not only can lead to confounding variables but also can adversely affect the internal and external validity of a study. Researchers should consider control variables as important as independent and dependent variables when designing a study. Without control variables, a researcher cannot make accurate claims about the impact of independent variables. Controlling for extraneous variables is particularly important when conducting research on human subjects. Because humans are complex beings, a number of confounding variables can affect the results of a study. Therefore, a researcher must eliminate any extraneous variables so dependent and independent variables can be isolated and quantified precisely.
Examples of Control Variables
To further explore how control variables can be used in research, three different examples will be examined. Each example is related to communication research in higher education. The first example explores how extraneous variables can be controlled when examining how new technology can affect student learning. If, for example, a researcher is interested in testing the effects of e-readers on reading comprehension in a particular course, a researcher would want to control for any other factors that might affect reading comprehension. In this example, e-readers are the independent variable and reading comprehension is the dependent variable. To accurately understand the effects of an e-reader on comprehension, a researcher might want to control for variables such as content knowledge and intelligence. This would ensure that the researcher knows the extent the independent variable, and not confounding variables, affects the dependent variable.
A second example examines how control variables can help researchers understand the relationship between cocurricular activities and communication competency. If conducting research on the relationship between a convocation program at a university and intercultural communication competency, a researcher would need to control for variables that could affect communication competency. In this instance, the dependent variable is intercultural communication competency, and the independent variable is a convocation program. If not controlled, variables such as experience traveling abroad or a course in intercultural communication might confound the results because of their influence on the dependent variable.
The third example examines the topic of student retention. In this example, a researcher is exploring how first-year seminars (independent variable) affect student retention (dependent variable). To ensure that this relationship is truly being examined, a researcher would need to control for other factors that might lead to student retention. Therefore, control variables in this experiment would be factors such as ACT/SAT scores, student housing, and involvement in sororities and fraternities.
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- Creating and Conducting Research
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