Krugman massages the numbers to show that the middle class has been left behind, including a chart measuring median (and mean) family income over the last 75 years.

FORBES: Paul Krugman Is a AAA Rated Security Gone Bad

This procedure centres the chart on the median, not the mode (if the two are different).

ECONOMIST: A la mode | The

The trouble is that this centres the fan chart on the mode of the distribution (the single likeliest outcome), and not necessarily on the median (the value that divides the outcomes, ranked by size, exactly in two) or the mean (the sum of the outcomes divided by the number of outcomes).

ECONOMIST: A la mode | The