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 independent variable on the dependent variable depends on the level of another independent variable. In this problem, the two factors are study group size and study environment, and the dependent variable is test performance.
2. Step 2: Analyze the first two statements. Both describe main effects: the first says quiet environments lead to higher scores regardless of group size, and the second says group study leads to better performance regardless of environment. These indicate independent effects without interaction.
3. Step 3: Examine the third statement. It describes differences in scores based on group size alone, without mentioning environment, so it also reflects a main effect rather than an interaction.
4. Step 4: Look at the last statement carefully. It says that students studying in groups do better in noisy environments, but students studying solo do better in quiet environments. This means the effect of group size on performance changes depending on the environment, which is the hallmark of an interaction effect.
5. Step 5: Conclude that the last statement most clearly suggests an interaction effect because the influence of one factor (group size) depends on the level of the other factor (environment), demonstrating that the two factors do not operate independently.