A study probing how cell phone use immediately before bed affects sleep was performed. In the study, the length of time it took participants to fall asleep in minutes while in a controlled environment was measured for two weeks. During the first week, the participants were not allowed to have their phones, but during the second week, the participants were allowed to have their phones. The data collected is below.

Participant 1 2 3 4 5 6 7 Time to fall asleep with phone 38 32 88 59 40 17 39 Time to fall asleep without phone 23 28 90 45 32 19 34