Alladi Ramakrishnan Hall

Universality in collective opinion: the voting case

Arnab Chatterjee

Department of Biomedical Engineering and Computational Science (BECS), Aalto University School of Science, Espoo, Finland

Election data represent an extremely precious source
of information to study human behavior at a large scale. The
behavior of certain macroscopic measurables show universal pattern
depending on the type of election. In proportional elections with
open lists, the number of votes received by a candidate, rescaled
by the average performance of all competitors in the same party
list, has the same distribution regardless of the country and the
year of the election. We provide the first thorough assessment
of this claim. Analyis of election datasets of several countries
with proportional systems confirm that a class of nations with
similar election rules fulfill the universality claim. Discrepancies
from this trend in other countries with open-lists elections are
always associated with peculiar differences in the election rules,
which matter more than differences between countries and historical
periods. Our analysis shows that the role of parties in the electoral
performance of candidates is crucial: alternative scalings not
taking into account party affiliations lead to poor results.
For the other weidely used system, the first-past-the-post,
a different set of universal behavior is observed.