Part III:  What is a heatmap… really?

A heatmap can be defined several different ways, but as they say, all roads lead to Rome. I find the 2 most useful ways of describing a heatmap are:

1 – A heatmap is an aggregate representation showing what areas a group of people fixated when viewing a webpage or email. The image shows where the sample group looked or didn’t look.  Well produced heatmaps should also take into account a reasonable percentage of peripheral vision. 

And

2 – A heatmap is a probability map which tells you what page content users are most likely to see. This is only true when the number of individual sessions used to create the heatmap is large enough.  At Eyetools, we recommend 15 people in most cases.  This number is based on what we have found gets our clients reliable results and the best cost-benefit ratio (bang for their buck).

Heatmaps are striking images, and very informative analysis tools.  However, they are just the tip of the iceberg when performing a proper analysis of eye movement data.  This is why companies who specialize in eye-tracking research have begun popping up. 

What can’t you learn from a single heatmap?

•    View order. Are users scanning the page in the most efficient way possible?  Are they forming a coherent message or are they lost? Sometimes a heatmap can be covered in "hot spots" but read through was very low.  More analysis is needed.

•    Copy vs. Layout Problems.   Heatmaps can help experimenters determine whether a page’s layout or copy is responsible for decreased viewing.  However, further analysis is needed to make a complete diagnosis.

•    How to improve page performance.   This is really knowledge that can only be gained through experience.  Viewing patterns can be affected by a number of different factors.  Heatmaps can help you to understand if there is a problem, but not how to specifically go about making changes.  (That’s why we're here. Please excuse the shameless plug.)

•    Variability.   By definition heatmaps do not have a measure of variability (error bar) associated with them.  I have a few thoughts, and (some rather interesting findings) about the variability in heatmaps and other eye-tracking metrics, but that is another discussion all together.  If anyone is particularly interested in discussing analysis at this level, let me know.

•    Time Components. Heatmaps do not have a time component. Time spent looking at a page element, or the page as a whole, is not represented at the heatmap level.