Stephen Zuro of Joliet Junior College wanted to determine whether an online homework system improved scores on a final exam. In the fall semester, he taught a precalculus class using the online homework system (which meant students did their homework online and received instant feedback about their answers along with helpful guidance). In the spring semester, he taught a precalculus class without the homework system (which meant students were responsible for doing their homework the old-fashioned way€”paper and pencil).

Professor Zuro made sure to teach the two courses identically (same text, syllabus, tests, meeting time, meeting location, and so on). The table summarizes the results of the two classes on their final exam.

(a) What type of experimental design is this?
(b) What is the response variable? What are the treatments in the study?
(c) What factors are controlled in the experiment?
(d) In many experiments, the researcher will recruit volunteers and randomly assign the individuals to a treatment group. In what regard was this done for this experiment?
(e) Did the students perform better on the final exam in the fall semester? Use an α = 0.05 level of significance.
(f) Can you think of any factors that may confound the results?

Could Professor Zuro have done anything about these confounding factors?

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Fall Semester 27 Spring Semester Number of students Mean final exam score Standard deviation final exam score 25 73.6 67.9 10.3 12.4