How do we get students to work harder? Standards in schools may be rising, which means that students are more likely to encounter failures along the road to mastery of a subject. What motivates them to keep getting up, after academically falling down?

This piece in the Atlantic describes the impact of different motivational interventions on students from different backgrounds. In the study, students wrote an essay for their teachers, and the teachers graded their essays like they normally would, adding comments to the essay about what the students need to revise. But the researchers intervened before the essays got handed back. This passage from the journalist's story describes a 2x2 factorial design. See if you can identify the IV, PV, and DV in this example.

... the researchers randomly attached one of two sticky notes to each essay. None of the students were aware that they were part of a study and thought their teachers had written the notes. Half of them received a bland message saying, "I'm giving you these comments so that you'll have feedback on your paper." The other half received a note saying, “I’m giving you these comments because I have very high expectations and I know you can reach them”—a comment intended to signal teachers' investment in their students' success.

Then teachers offered the students an opportunity to revise their essays.

The results were striking. Among white students, 87 percent of those who received the encouraging teacher message turned in new essays, compared to 62 percent of those who got the bland note. Among African American students, the effect was even greater, with 72 percent in the encouraged group doing the revision, compared to only 17 percent of those randomly chosen to get the bland message. And the revised essays received higher scores from both the students' teachers and outside graders hired for the study.

a) List this study's IV, PV, and DV.

b) For each IV and PV, indicate: Is it within groups or independent groups? Is it manipulated or measured?

c) Using the results reported in the quoted passage, create a graph of the results.

d) Using marginal means or using your visual inspection of the graph you made in (c), estimate and describe this study's main effects and interactions.

e) Challenge question: Like most experimental studies, this one used additional dependent variables other than the primary one described above. In the study described, the researchers also measured students' trust in their teachers. What results do you think they may have found? Sketch a graph showing the results you'd hypothesize for this DV.