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Virginia Policy Review
Figure 6: Neutral ensembles based on the mean-median gap tell roughly the same story as seats or EG.
3.2 Virginia’s neutral baseline The chief advantage of the ensemble method is that it allows us to establish a baseline for each districting metric in the state that fully incorporates the relevant rules and guidelines, as well as the underlying political geography—the physical, demographic, and electoral data from Virginia itself forms the population network from which districting plans are cut. This is extremely important because the normal behavior of districts varies quite a bit from state to state and from one time period and legal context to another. We have already seen the normal range of partisan metrics (seats, efficiency gap, and mean-median gap) above. Compactness and geographic splitting over the ensemble are recorded in Figure 7. Finally, district-level boxplots are shown in Figure 8 for each party’s share of the vote and the BVAP%.