Question: Refer to Original Source 5 on the CD, "Distractions in Everyday Driving." Table 14 on page 51 provides 95% confidence intervals for the average percent of time drivers in the population would be observed not to have their hands on the wheel during various activities while the vehicle was moving, assuming they were like the drivers in this study. The confidence intervals were computed using a different method than the one presented in this book because of the type of data available, but the interpretation is the same.
a. The confidence interval accompanying "Reading/writing" is from 4.24% to 34.39%. Write a few sentences interpreting this interval that would be understood by someone with no training in statistics. Make sure you are clear about the population to which the result applies.
b. Repeat part a for the confidence interval for "Conversing."
c. Refer to the interval in part a. Write it as a 95% confidence interval for the average number of minutes out of an hour that drivers who were reading or writing would be observed to have their hands off of the wheel.
d. Notice that in Table 14 some of the intervals are much wider than others. For instance, the 95% confidence interval for the percent of time with hands off the wheel while not reading or writing is from 0.97 to 1.93, compared with the interval from 4.24 to 34.39 while reading or writing. What two features of the data do you think are responsible for some intervals being wider than others?