A university surveys how study group size (solo, duo, group) and study environment (quiet, noisy) affect test performance. Which of the following conclusions most clearly suggests an interaction effect between the two factors?

• A. Students who study in quiet environments score higher than students who study in noisy ones, regardless of group size
• B. Students who study in groups generally perform better than those who study alone, regardless of environment
• C. Solo and group sizes produced similar, higher scores overall, but duo group sizes were overall lower
• D. Students studying in groups in noisy environments tend to perform better, whereas students studying solo in quiet environments tend to perform better

Answer: (D)

Verified step by step guidance

1. Step 1: Understand the concept of interaction effect. In statistics, an interaction effect occurs when the effect of one factor on the outcome depends on the level of another factor. This means the influence of one variable changes depending on the other variable.
2. Step 2: Identify the two factors in the problem: study group size (solo, duo, group) and study environment (quiet, noisy). The outcome is test performance.
3. Step 3: Examine the statements to see if the effect of one factor depends on the other. Statements that say one factor affects performance regardless of the other (e.g., "Students who study in quiet environments score higher regardless of group size") indicate no interaction because the effect is consistent across levels of the other factor.
4. Step 4: Look for a statement where the effect of one factor changes depending on the other factor. For example, "Students studying in groups in noisy environments tend to perform better, whereas students studying solo in quiet environments tend to perform better" shows that the best performance depends on the combination of group size and environment, indicating an interaction effect.
5. Step 5: Conclude that the presence of an interaction effect is demonstrated when the impact of one factor (study group size) on test performance varies depending on the level of the other factor (study environment), as described in the correct answer.