Simplicity and clarity
Comparing lifetime saving curves

A variant of the "half-baked" disease

The disease of the "half-baked" (see here) is in fact widespread.  The Wall Street Journal and other media outlets have a liking for this particular feature in their bar charts.

In the chart on the right, Wsjomnicomthe half-baked bar rears its head in 2005.  In this variant of the disease, the 2004 bar is split into two halves so that we can compare first half 2004 and first half 2005.

Two numbers do not a trend make and so the extra data point only gives us false comfort.  While 2005 first half compares poorly to 2004 first half, we don't know how 2005 first half compares to other such periods in the bank's history.  In reading such charts, avoid the tendency to generalize.

Why not split every bar so that we can accurately judge the size of the half-baked 2005 bar?  Alternatively, remove the gray bars and draw in a projected full-year 2005 number.

Reference: "Omnicom Lands Bank of America", Wall Street Journal, Sept 1 2005.


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