Reconsider the bicycle commuting time study (Example 6.2) and the sleep deprivation study (Exploration 6.2).

a. In what primary way do these studies diff er from the dolphin therapy and yawning studies from Chapter 5?
b. Are both of these studies (sleep deprivation and bicycle commuting time) randomized experiments, are both observational studies, or is there one of each type (if so, which is which)?

c. Did we use simulation-based or theory-based methods to analyze these studies?
d. Which, if any, of these two studies uses a two-sided alternative?
e. With which of these two studies did we find strong evidence that there was a cause-and-effect relationship between the variables?