This work posted on the ArXiv here, summarize the initial work done by Christy Vaughn Graves and Jonathan Mattingly between Summer 2013 and Fall 2014. It uses the same basic methodology as the subsequent papers: generate an ensemble of redistricting plans, analysis their properties, and then compare an existing plan of interest to the ensemble of maps.
The central idea being that maps which were outliers in the ensemble were should be seen as unrepresentative.
This analysis did not include the VRA or county splitting terms in the score function as latter works did. The work did look at the typical most african american district in each plan after the plan had been drawn.
We also did not have access to the true length of the boundary between various VTDs. Instead we used an approximation which assumed each district was circular and that the boundary was equally shared between neighbors. This work also used a much smaller number of maps. There were also a small bug in the code which was fixed in subsequent summers.