Taxonomy of Data Visualization Methods - Data Visualization: A Successful Design Process - page 141

Description : With further similarities to small multiples, heatmaps enable us to
perform rapid pattern matching to detect the order and hierarchy of different
quantitative values across a matrix of categorical combinations. The use of a color
scheme with decreasing saturation or increasing lightness helps create the sense of
data magnitude ranking.
Parallel sets (or parallel coordinates)
Data variables : Multiple x categorical, multiple x quantitative-ratio.
Visual variables : Position, width, link, color-hue.
Description : Parallel sets offer a unique way of visually exploring and analyzing
datasets. The technique involves plotting all your data on to a series of axes, one for
each of the variables you are interested in examining. This creates pathways that
show the connections between the breakdown of values contained within your data
for each variable. They are useful for learning about the potential correlations and
consistencies that exist in our datasets. You'll notice certain similarities with the
function of Sankey diagrams.