Believe it or not, the difference in the way the Democrats and
Republicans react to the performance of the U.S. economy is
clarified by a mathematical distinction studied in elementary
school. The distinction is between the mean, which the
Republicans emphasize, while the Democrats prefer the median.
Before turning to the economy, let me review a little fourth-
grade arithmetic. The mean of a set of numbers is simply the
average, and it is obtained by adding the numbers in the set and
dividing by how many there are. The median of a set of numbers
is obtained by listing the numbers in the set in ascending order
and locating the middle number in the list. The same set of
numbers can have a mean and a median, which differ
significantly. A real estate agent, for example, informs you
that the mean price for a house in a certain neighborhood is
$500,000 and implies that there are many houses above that price
in the neighborhood. Not necessarily. If most of the houses sell
for somewhere between $100,000 and $200,000,