In an editorial (subscription required), the Wall Street Journal compares the $71,000 average salary of Chicago’s teachers with the $47,000 average salary of the people who pay for the teachers, implying that the teachers are ripping off taxpayers. The teachers indeed may be ripping off taxpayers, but supporting that assertion with reference to “average” salaries is a misleading tactic that conservatives use all the time to attack government employees. Using a simple “average” to compare the salaries of two groups is statistically valid only if the groups are similar in composition.

If the WSJ wanted to be objective, a better approach would be to compare the average Chicago public school teacher salary with the salary of teachers in private schools. If for some technical reason this would not work, then the WSJ could compare the average teacher salary with the average salary of a general group of private workers whose age, education, and work experiences are similar to the teachers. Until the WSJ and other conservatives actually begin to analyze government compensation issues rationally instead of emotionally, it wouldn’t be wise for anyone to put much faith in any of their conclusions.