Question: How does cell phone use affect driving performance? Strayer, Drews, and Johnston (2003) had undergraduates drive a high-fidelity automobile simulator as their only task and while engaged in a hands-free cell phone conversation. Participants applied the brake when the brake lights of the vehicle in front of them came on. The numbers that follow are reaction times in seconds. Analyze the data and write a conclusion about the effect of cell phone conversations on driving performance. Carry four decimals in your calculations.

No cell phone                Cell phone

     1.03                            1.12

     0.97                            1.31

     0.82                            0.96

     1.09                            1.08

     1.15                            0.99

     0.72                            1.04

     0.95                            1.16

     0.87                            1.22