Everybody knows what the word "average" means and that it is the most widely used simple statistic. But it can be highly misleading. That occurred to me in two recent news reports. One article a week ago detailed how households would be affected if we returned to the tax rates in effect from 1994 to 2001, including an elaborate tabulation of the average annual increase for taxpayers by state. The second article dealt with average life expectancies relating to the solvency of Social Security and Medicare. In the first article, the tax increases detailed ranged from an average of about...