The file “homework experiment data.sav” (or “homework experiment.xls”) includes data from a simulated experiment in which children were given different types of homework. Sixth graders were randomly assigned to one of three groups (the Type variable in the data): group 1 was assigned drill sheet-derived homework in Social Studies at least three times per week. Group 2 was assigned practice homework (homework designed to practice the important concepts from that day’s lesson in Social Studies), also at least 3 times per week. Group 3 was assigned extension homework on the same schedule. Extension homework is designed to extend the lesson taught in school, often with additional content. At the end of six weeks students were administered a standardized measure of sixth-grade Social Studies achievement (M=50, SD=10).

a. Consider drill homework to be the norm. Analyze the results of this experiment using dummy coding, and comparing the other two types of homework with this norm.

b. Analyze the experiment using effect coding. Which group did you choose as the contrast group (the group with −1s for the effect-coded variables)? Explain why.