Chernoff faces showcase multivariate data in a symbol of a human face. Every facial feature represents values of the variables by its shape, size, orientation, and placement. The concept behind using faces is that humans are good at recognizing faces and notice subtle changes or differences.
Variables should be carefully chosen because we are more keened to perceive certain facial features than others. (e.g. eye size and eyebrow-slant have been found to carry significant weight).
Pros:
- It can be a quick way to display datasets. Especially the ones that involve emotions, such as qualitatively assess the performance of a campaign.
- It can be used to represent multi-dimensional data in a very compact manner.
- If used appropriately, it can be a fun way to showcase the mundane data.
Cons:
- Difficult to make quantitative assessments with the faces.
- Unpractical for large datasets since it would be too small to see the details.
- Could be offensive to relate certain type of look to something negative.
Good Examples:
Eugene Turner - Life in Los Angeles (1977)
Poor neighborhoods are represented with emaciated, scowling faces, and wealthy neighborhoods are represented by grinning ones. The face symbols are quite intuitive to read and help raise awareness of inequality issues in LA.
A fun way of storytelling for displaying more details of presidential election results. It's quite humorous to give Clinton pearl earrings for the areas that has a higher amount of campaign spendings.
Using facial expressions to represent a team's Key Performance Indicator is symbolically appropriate and very intuitive.
Bad Examples:
The graph becomes difficult to read when visualizing a large amount of data. There is also a disconnection between the subjects (beer vs wine) and facial feature.
Why is low unemployment represented by a happy grin, and high unemployment with a frown? Why are areas with a high proportion of women in the workforce represented with angry eyes?
How can the height of someone’s face speak to their propensity for violent crime?