Which statement best describes extraneous variables?

Which statement best describes extraneous variables?

• A. They can affect the DV if not controlled and can be maintained or eliminated.
• B. They always affect the DV and cannot be controlled.
• C. They are the same as the IV.
• D. They are only measurement errors.

Answer: (A)

Extraneous variables are any factors other than the manipulated variable that could influence the outcome of a study. They pose a threat to internal validity because if they differ across conditions and are not kept constant or removed, they can produce effects that look like the manipulation caused them. The best description is that they can affect the dependent variable if not controlled, and they can be maintained (held constant) or eliminated (controlled away) to prevent them from confounding results. This captures both the potential impact they have and the two primary ways researchers deal with them. Why the other ideas don’t fit: extraneous variables are not the same as the manipulated variable, so they aren’t simply another factor you’re changing on purpose. They aren’t only measurement errors, since they include any other uncontrolled influence like participant variables or situational factors. And they don’t have to always affect the DV; with proper control, they may have no impact on the outcome.

Extraneous variables are any factors other than the manipulated variable that could influence the outcome of a study. They pose a threat to internal validity because if they differ across conditions and are not kept constant or removed, they can produce effects that look like the manipulation caused them.

The best description is that they can affect the dependent variable if not controlled, and they can be maintained (held constant) or eliminated (controlled away) to prevent them from confounding results. This captures both the potential impact they have and the two primary ways researchers deal with them.

Why the other ideas don’t fit: extraneous variables are not the same as the manipulated variable, so they aren’t simply another factor you’re changing on purpose. They aren’t only measurement errors, since they include any other uncontrolled influence like participant variables or situational factors. And they don’t have to always affect the DV; with proper control, they may have no impact on the outcome.