Table 9.3 indicates the population (in millions) and the number of violent crimes (in millions) in the United States from 1982 to 1991, as reported in the World Almanac and Book of Facts (1993, p. 948). (Thankfully, both numbers and rates of violent crime started dropping in 1992 and have continued to do so. Thus, the data for this exer­cise end in 1991 to illustrate the increasing trend up to that time.)
a. Draw two line graphs representing the trend in violent crime over time. Draw the first graph to try to convince the reader that the trend is quite ominous. Draw the second graph to try to convince the reader that it is not. Make sure all of the other features of your graph meet the criteria for a good picture.
b. Draw a scatterplot of population versus vio­lent crime, making sure it meets all the criteria for a good picture. Comment on the scatterplot. Now explain why drawing a line graph of violent crime versus year, as in part (a) of this exercise, might be misleading.
c. Rather than using number of violent crimes on the vertical axis, redraw the first line graph (from part [a]) using a measure that adjusts for the increase in population. Comment on the differences between the two graphs.