[mat-wg] color blindness and color meaning association

Hi all,

TL;DR - red/green color palettes should be avoided in data
        visualiations, please pick something else!

Yesterday I saw Christian Teuschel present on the "Jedi" tool at SINOG,
and two things stood out:

    A) the data visualisations do not attempt to accomodate for people
       who are color blind, in fact, the worst colors possible were
       picked

    B) by using using common traffic light colors (green, orange, red) 
       an implicit judgement is made on the meaning of the data (traffic
       crossing an internet exchange was seemingly favored over private
       peering)

To point (A) - red–green color blindness which affect a substantial
portion of the human population. In the US, about 7 percent of the male
population (or about 10.5 million men) and 0.4 percent of the female
population either cannot distinguish red from green, or see red and
green differently from how others do (Howard Hughes Medical Institute,
2006). There are quite some pointers as to how to design color palettes
which accomodate everyone.
    
    http://www.somersault1824.com/tips-for-designing-scientific-figures-for-color-blind-readers/
    http://blog.usabilla.com/how-to-design-for-color-blindness/

B) As I understand the "Jedi" tool, it shows matrixes of what traffic
between atlas probes leaves the country, and what traffic remains within
the country - offering insight into a reflection on a country's internal
routing arrangements. I'm a big fan of keeping local traffic local, so
the tool certainly has value.

However, the tool displays traffic which passes over an IXP within the
country as green, and traffic that says within the country but didn't
cross an IXP as "orange". Since the majority of internet traffic flows
over direct, private interconnections between ASNs, signifying that
traffic as "orange", has the potential to be taken as a "wrong", rather
then as an arbitrary datapoint. I suggest that the Jedi tool either uses
the same color for ixp and non-ixp "within country" traffic (and perhaps
a small icon is used to signify the additional data attribute that an
IXP was observed in the traceroute), or that the jedi tool uses entirely
arbitrary colors that have no inherent meaning like the traffic light
colors do.

Kind regards,

Job