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HEAT MAP – Graphical and Pictorial Representation of Data

A heat map can be best described as a colored visual representation of data. It provides a platform to represent comparisons of categorical data through a colored medium. Heat maps are typically constructed as a table by using a continuous range of colors and colored squares to represent the data. The variations in data can be spotted via the varying colors of the heat map table.

Heat maps gained greater popularity during the economic recession that commenced in 2008. They were widely used to observe the foreclosure rates in various states and to compare them to the heat maps from the previous months. A heat map can be used with all types of data ranging from the representation of the number of foreclosures to the spreads of credit default swaps.

The figure given below represents a heat map that depicts foreclosures data. It represents the parts of the U.S. that experienced high rates of foreclosure in a dark color while states with low foreclosure rates are depicted in lighter colors. A color-gradient legend typically accompanies a heat map to specify the data.


As evident from the above figure, in Tableau heat maps are typically constructed as a table of colored squares.

A heat map is created by placing one or more dimensions on the Columns shelf and one or more dimensions on the Rows shelf. One can then select the mark type as Square and place a measure of interest on the Color shelf. Of course, one is not limited to the type of heat map exhibited above. Users can build any view that is meaningful to them. For example, one can color-encode the data using a dimension as well as size-encode and shape-encode the data. Some of these views certainly stretch the definition of a heat map.


ClickTale’s and Crazyegg’s heat maps allow for the optimization of websites conversion rates and usability by visualizing the visitors’ every mouse move, click, and scroll. Heat maps are aggregated reports that visually display what parts of a webpage are looked at, clicked on, focused on and interacted with by thousands of online visitors.The first thing one needs to know about heat maps is that they represent the areas that people have clicked on your website – the brighter the area on the screen, the more number of people have clicked on that spot. The bright areas on the website represent the ” hot” areas.

Hence, one can use information from heat maps to improve their websites by determining which design elements are performing best and which ones are not getting noticed. For example, if you have published two separate banners about an upcoming sale and notice that one received significantly more clicks than the other, you may decide to revise or re-position the under-performing graphic.