Multi-district preference modelling
  Generating realistic artificial preference distributions is an important part
of any simulation analysis of electoral systems. While this has been discussed
in some detail in the context of a single electoral district, many electoral
systems of interest are based on multiple districts. Neither treating
preferences between districts as independent nor ignoring the district
structure yields satisfactory results. We present a model based on an extension
of the classic Eggenberger-Pólya urn, in which each district is represented
by an urn and there is correlation between urns. We show in detail that this
procedure has a small number of tunable parameters, is computationally
efficient, and produces "realistic-looking" distributions. We intend to use it
in further studies of electoral systems.
