Question: Researchers speculate that drivers who do not wear a seatbelt are more likely to speed than drivers who do wear one. The following data were collected on a random sample of 20 drivers who were clocked to see how fast they were driving (miles per hour), and then were stopped to see whether they were wearing a seat belt (Y = yes, N = no).
Do these results support the claim that the mean speed is higher for the population of drivers who do not wear seatbelts than for the population of drivers who do?
a. Carry out the five steps of hypotheses testing using the unpooled procedure.
b. Repeat part (a) using the pooled procedure.
c. Compare the unpooled and pooled results and discuss which procedure is more appropriate.
d. Carry out the unpooled test using the rejection region approach with a = .05.