Doing homework is a nightly routine for most school-age children. The article Family Involvement with Middle-Grades Homework:

Question:

Doing homework is a nightly routine for most school-age children. The article €œFamily Involvement with Middle-Grades Homework: Effects of Differential Prompting€ (Balli, S. J., J. F. Wedman, and D. H. Demo, 1997), examines the question of whether parents€™ involvement with their children€™s homework is associated with improved academic performance. Seventy-four sixth graders and their families participated in the study. The students, similar in academic ability and background, were enrolled in one of three mathematics classes taught by the same teacher; researchers randomly assigned each class to one of the three treatment groups.
Group I, student/family prompt: Students were prompted to seek assistance from a family member, and family members were encouraged to provide assistance to the students.
Group II, student prompt: Students were prompted to seek assistance from a family member, but there was no specific encouragement of family members to provide assistance to the students.
Group III, no prompts: Students were not prompted to seek assistance from a family member nor were family members encouraged to provide assistance to the students. The researchers gave the students a posttest, with the results given here:

The researchers concluded that higher levels of family involvement were not associated with higher student achievement in this study.
a. What is the population of interest in this study?
b. Based on the data collected, to what population can the results of this study be attributed?
c. What is the effective sample for each of the treatment groups; that is, how many experimental units were randomly assigned to each of the treatment groups?
d. What criticisms would you have for the design of this study?
e. Suggest an improved design for addressing the research hypothesis that family involvement improves student performance in mathematics classes.