Which phenomenon best illustrates a confounding variable in a study about study time and test scores?

• A. Random sampling.
• B. Ecological validity.
• C. Reliability.
• D. Confounding variable.

Answer: (D)

When a factor influences both how long students study and how well they do on a test, it can create a misleading link between study time and test scores. This kind of factor is a confounding variable. It distorts the observed relationship because the apparent effect of study time may actually be partly due to this other variable. For example, a student’s overall motivation or prior knowledge could lead to more effective studying and higher scores at the same time, making it look like more study directly causes better results when part of the effect comes from motivation or prior knowledge. Controlling for such variables in research helps reveal the true impact of study time.

Random sampling is about choosing participants in a way that represents a larger population, not about variables that distort relationships. Ecological validity concerns whether findings generalize to real-world settings. Reliability relates to the consistency of measurements across time or items.