A yoga instructor collected student data. He found that students who had less sleep did not tend to burn more or fewer calories during class. What can he conclude?
1)There is no correlation between amount of sleep and number of calories burned.

2)There may or may not be causation. Further studies would have to be done to determine this.

3)There is a correlation between amount of sleep and number of calories burned. There is probably also causation. This is because there is likely an increase in the number of calories burned with an increase in the amount of sleep.