13.38 Use of animated agents in a multimedia environment. Multimedia learning environments are designed to enhance learning by providing a more hands-on and exploratory investigation of a topic. Often, animated agents (human-like characters) are used with the hope of enhancing social interaction with the software and thus improving learning. One group of researchers decided to investigate whether the presence of an agent and the type of verbal feedback provided were actually helpful.22 To do this, they recruited 135 college students and randomly divided them among four groups: agent/simple feedback, agent/elaborate feedback, no agent/simple feedback, and no agent/elaborate feedback. The topic of the software was thermodynamics. The change in score on a 20-question test taken before and after using the software was the response.

  1. (a) Make a table giving the sample size, mean, and standard deviation for each group.

  2. (b) Use these means to construct an interaction plot. Describe the main effects for agent presence and for feedback type as well as their interaction.

  3. (c) Analyze the change in score using ANOVA. Report the test statistics, degrees of freedom, and P-values.

  4. (d) Use the residuals to check model assumptions. Are there any concerns? Explain your answer.

  5. (e) Based on parts (b) and (c), write a short paragraph summarizing your findings.