Heat Maps: Part III – How to Read One?

In Part I and Part II of the series, you have seen “What are Heat Maps?” and “Why use them?”. In the final post of this series, we will be focusing on “How to Read a Heat Map?”

Here are few Demos you can use while reading this post:

demobutton1 demobutton2 demobutton3

Heat maps represent information from databases and spreadsheets visually as rectangles, with important characteristics of individual data items used to determine the size, color and layout of the rectangles. In general:

  • Size maps to relevance, such as the size of an opportunity or the total budget for a project.
  • Color maps to urgency; like the potential upside of an opportunity, the cost or time overrun on a project, risk levels, or the number of security incidents at a network site.
  • Grouping of rectangles is tied to category information, such as department, manager, location, or type of product or application.

When these three visual cues are combined in a heat map, it becomes straightforward to:

  • Identify which information is the most important, for example, the opportunities or threats that involve the largest financial impact, since the associated rectangle or group of rectangles is large.
  • See urgent issues such as particularly high risks or overruns, since the associated rectangles have a color that stands out from other data.
  • Discover trends or interesting patterns, such as generally higher or lower performance or risk associated with a particular region, manager, type of product, etc., since grouping related records together spatially allows detailed data represented by size or color to be seen in context.

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