Another Heatwave Chart

Here's another take of the heatwave chart, from AP. How does AP compare to NYT?

The Good

• AP uses more relevant metrics, namely "extreme maximum temperature" and "above average temperature from normal".  The NYT chart picks out any city that reached the 100 F threshold, even for just one minute in a given week.
  
  
• Both use the small multiples design: the heatwave-metric dimension makes more sense than NYT's week-of-the-month dimension.
  
  
• Instead of scatters of dots, AP gives us density maps, telling us more while using less clutter. We immediately see which regions were most affected.
  
  
• The titles and annotations indicate that this chart has a message while the NYT chart could just be a container of data.
  
  

The Bad

• One imagines that two graphic designers produced a map each, their manager preferred the bottom one but decided to give the other map a supporting role, hiding it in the corner.  The staff is merry but the reader is dizzy. The metric and the scale of the map shifted simultaneously. A small multiples design works only if one and only one dimension is changed from chart to chart.
  
  
• One designer preferred an explicit scale legend; the other annotated patches of color in lieu of a legend.  Different scales on one graphic confuses the reader.  Particularly so when the two maps use the same colors to represent different metrics!
  
  
• I couldn't bring myself to comment on the convoluted, ungrammatical language of "extreme maximum temperature" and "above average temperature from normal".
  
  
• Where is the time dimension?  Without time, "maximum temperature" is meaningless.
  
  
• The text should always align with the picture: show us where Las Vegas and Death Valley are.
  
  
• As with the NYT map, state boundaries are superfluous to the message.

Here, the manager had the right instinct.  The large map showing regions in the country that were experiencing abnormally high temperatures presents a strong, clear message.  The small map is excessive.