A teacher ran a study to see whether people would score better on a math assignment with or without music playing. After grading the assignment, he asked them to report how many songs they listened to. He found that students in his class who listened to more songs while doing homework at home had a lower grade (out of 100).

1. What kind of data structure is this? (.5)
2. Can the researcher infer causality?(.5)
3. What are the variables, if any? (Write N/A if there is none) (1.5)
4. State:variable,if it is independent/dependent,if it is discrete/continuous.
5. What is the most likely scale of measurement for each variable? (Write N/A if there is none) (.5)