Frequency polygons are an alternative to histograms. There is no right or wrong choice when it comes to deciding whether to use a histogram or a frequency polygon with a particular continuous variable; the best strategy is to mix it up a bit so that you are not using the same chart type repeatedly. Figure 3.10 contains the frequency polygon for data similar to that used in Figure 3.8 except this time it includes the ages of non- Hispanic respondents instead of Hispanic respondents. Frequency polygons are created by placing a dot in the places where the tops of the bars would be in a histogram and then connecting those dots with a line.
Another type of continuous variable that could be graphed using a frequency polygon is the number of female sergeants in police departments and sheriffs’ offices. Nationwide, police agencies are seeking not merely to recruit and retain female officers but also to promote them to ranks with supervisory and management responsibilities.