An uncontrolled factor known or suspected to exert influence on the dependent variable is called what?

• A. Confounding Variable
• B. Control Variable
• C. Mediating Variable
• D. Moderating Variable

Answer: (A)

Uncontrolled factor that can influence the dependent variable is a confounding variable. This type of variable threatens internal validity because it can create or mask an association between the manipulated variable and the outcome, making it unclear whether observed effects come from the treatment or from that outside factor. The key idea is that the confounding variable is not controlled or accounted for, yet it has a relationship with both the variable you’re manipulating and the result you’re measuring, which can bias conclusions.

This differs from a control variable, which you intentionally hold steady across conditions to prevent it from affecting the outcome. A mediating variable is part of the mechanism by which the independent variable influences the dependent variable—it's the why or how of the effect. A moderating variable changes the strength or direction of that relationship, meaning the effect varies depending on its level.

Example: if you’re testing a study skills program on test scores, prior math ability could be a confound if it affects both likelihood of engaging with the program and the test outcome. If you measure and balance math ability, you reduce the confound. If the program works by increasing motivation, motivation is a mediator. If the program’s effectiveness differs by age, age is a moderator.