EXAMPLE 3 Tuition and fees in Illinois

There are 116 colleges and universities in Illinois. Their tuition and fees for the 2009–2010 school year run from $1974 at Moraine Valley Community College to $38,550 at the University of Chicago. Figure 11.2 is a histogram of the tuition and fees charged by all 116 Illinois colleges and universities. We see that many (mostly community colleges) charge less than $4000. The distribution extends out to the right. At the upper extreme, two colleges charge between $36,000 and $40,000.

The distribution of tuition and fees at Illinois colleges, shown in Figure 11.2, has a quite different shape from the distribution in Figure 11.1. There is a strong peak in the lowest cost class. Most colleges charge less than $8000, but there is a long right tail extending up to almost $40,000. We call a distribution with a long tail on one side skewed. The center is roughly $8000 (half the colleges charge less than this). The variability is large, from $1974 to more than $38,000. There are no outliers—the colleges with the highest tuition just continue the long right tail that is part of the overall pattern.