Puzzle: Hoped to Learn What? Teens & Music

Today’s Puzzle of the Day concerns a newly published study.

The question is: What, if anything, did the researchers hope to learn by doing this research? The study is:

Using Ecological Momentary Assessment to Determine Media Use by Individuals With and Without Major Depressive Disorder,” Brian A. Primack, MD, EdM, MS [pictured here], et al., Archives of Pediatric and Adolescent Medicine, 165(4), 2011, pp. 360-365. (Thanks to investigator Scott Langill for bringing this to our attention.) The authors explain:
“…participants were asked whether they were using the following 5 types of media: television or movies, music, video games, Internet, and print media, such as magazines, newspapers, and books….  Of the 106 participants, 46 were diagnosed as having MDD [major depressive disorder]….
“CONCLUSIONS Major depressive disorder is positively associated with popular music exposure and negatively associated with reading print media such as books.”

BONUS QUESTION: What, if anything, did they actually learn?

BONUS ALMOST-QUASI-RHYTHMIC CHANT OF THE DAY: “Correlation implies causation. Or maybe not. Or maybe something else. This explains everything. Or maybe not.”