Independent variable manipulation – UGC NET Question

The independent variable is the factor that the researcher intentionally varies or manipulates in an experiment to determine its causal effect on the dependent variable. It represents the presumed cause in a cause–effect relationship. By changing the levels of the independent variable, researchers can observe corresponding changes in outcomes. Because the stem specifies the variable that is deliberately manipulated to examine its effect on another variable, it correctly refers to the independent variable.

Option A:
Control variables are held constant across conditions to prevent them from influencing the dependent variable, but they are not the primary variables being manipulated to test hypotheses. Their purpose is to strengthen internal validity rather than to represent the main cause under investigation. Thus, control is not the right term for the manipulated variable described in the question.

Option B:
Extraneous variables are any variables other than the independent variable that may affect the dependent variable if not controlled or randomised. They are potential sources of error or alternative explanations for observed effects. Since the stem describes a variable that is deliberately manipulated, extraneous does not fit.

Option C:
Independent variables are central to experimental design because manipulating them allows researchers to test causal hypotheses in a controlled way. For example, different teaching methods can serve as independent variables when studying their impact on achievement. This focus on deliberate manipulation matches the description in the stem, making independent the correct answer.

Option D:
A moderator variable is one that affects the strength or direction of the relationship between an independent and dependent variable, but it is not necessarily the variable being experimentally manipulated in the main design. Moderators help explain under what conditions a particular effect occurs. Therefore, moderator is not the term the stem is seeking.