Recall Exercises 7.2.33, 7.2.34, and 7.2.35 in which researchers explored the effects on driving with various types of cell phone use. In particular, they were interested in comparing the effects of text-based media and picture-based media. The researchers had their subjects use a driving simulator and follow the car in front of them that was programmed to travel at various speeds between 55 and 65 mph. Time headway is the time between the front of the car in front of you and the front of your car; the subjects were instructed to keep their time headway at 2 seconds. The researchers measured the variability in this time over the course of the study. A variability number of 0 would mean they kept it at a constant 2 seconds and the higher the variability, the more difficulty the subject had at maintaining this distance. The researchers measured the time headway data when the subjects were instructed to scroll through Facebook messages that consisted of just text. They also measured this when the subjects were instructed to scroll through Instagram pictures that did not contain any text. The order of these conditions was randomized. The results, in seconds, are in the file TimeHeadwayVariability. We want to decide whether there tends to be a difference in the time headway variability while looking at text (Facebook) compared to looking at pictures (Instagram). 

a. What are the explanatory and response variables in this study and what types of variables are they (categorical or quantitative)? 

b. State the hypotheses either in words or using appropriate symbols. 

c. Put the data in the Matched Pairs applet. What is the value of the statistic that will be used in the study and what does it represent? 

d. Randomize at least 1,000 times and determine a p-value. 

e. Is there strong evidence that there is a difference in the average time headway variability while looking at text (Facebook) on the phone compared to looking at pictures (Instagram) on the phone?

Data from Exercises 7.2.33

Researchers at Arizona State University (McNabb & Gray, 2016) explored the effects on driving with various types of cell phone use. In particular, they were interested in comparing the effects between text-based media and picture-based media. They had their subjects use a driving simulator and requested that they stay two seconds behind the car in front of them. The car in front traveled between 55 and 65 mph and was programmed to come to a complete stop eight times during the simulation. One of the variables they measured was the reaction time for the subjects to brake when the car in front of them stopped. They measured this when the subjects were instructed to scroll through Facebook messages that consisted of just text. They also measured this when the subjects were instructed to scroll through Instagram pictures that did not contain any text. The order of the conditions was randomized. The results, in seconds, are in the file BrakeReactionTime. We want to decide whether there is a difference in the average braking reaction time when looking at text (Facebook) on your phone while driving and looking at pictures (Instagram) on your phone while driving