According to recent United Nations figures, the annual intentional homicide rate is 4.7 per 100,000 residents in the United States and 1.0 per 100,000 residents in Britain.
a. Compare the proportion of residents of the two countries killed intentionally using the difference of proportions. Show how the results differ according to whether the United States or Britain is identified as Group 1.
b. Compare the proportion of residents of the two countries by using the relative risk. Show how the results differ according to whether the United States or Britain is identified as Group 1.
c. When both proportions are very close to 0, as in this example, which measure do you think is more useful for describing the strength of association? Why?