With the upcoming redistricting cycle, there are a number of questions about how ensembles can, will, and should be used to audit and restrict gerrymandering.
We have prepared a slide deck illuminating how the ensembles have been used to legally challenge plans during the last redistricting cycle. We have also examined some of the new indices that are being put forward as measures of gerrymandering. Under a certain set of votes, it is possible to “game” these indices, in the sense that plans can be typical of an ensemble according to multiple indices while still being gerrymanders.
Finally, for the North Carolina general assembly, we demonstrate the fragility and possible choices when it comes to county clustering.
The slides are available here.