Based on 2012 results only, which state gerrymander flipped the most seats?

[Adam Griffin]

My metric is actually much easier to compute than some of the ones proffered to judges in hopes of finding a justiciable standard.

What you want is my computation of SKEW.
1. Find the PVI for the state as a fraction (or divide the percent by 100) and multiply that by 4 times the number of districts. This is the expected excess in the delegation for the party in a neutral map. Count Republicans as a negative number.
2. Find the PVI's of the actual districts. Count 0 for each highly competitive district (PVI 0 or 1), +1 for all other Democratic districts, and -1 for all other Republican districts. The total is the expected excess in the delegation under the actual map.
3. Take the number from step 2 and subtract the number from step 1. Express a negative number as a positive number in favor of the Republicans. The resulting positive number is the SKEW score, and lower numbers are closer to the ideal partisan fairness.
2A. You can substitute the actual delegation for the hypothetical delegation based on PVIs.

AZ is R+7. 4 times that percentage is -28%, and times 9 seats is -2.52 (rounded to -3), which is the neutral expectation. The map has 1 highly competitive CD (AZ-9), 2 Dem CDs (AZ-3,7) and 6 Pub CDs for a partisan expectation of -4. The SKEW is -1 or R+1. Over the decade it should slightly favor the Pubs.

The actual delegation is 4D, 5R or an actual excess of -1. Compared to -3 that gives a current SKEW of D+2, which gets howls from the Pubs. But unless the district PVI's are way off then either the Dems are overperforming or the Pubs are underperforming the map.

edit: Based on 2012 results only the delegation is 5D 4R so the skew is D+4.

Perhaps it has already been answered, but how do you define "competitive"?

[Adam Griffin]

Thanks for the answers - and wow, I'm an idiot - you had already answered that (at least in the primary way I needed to know)...in the post I quoted, no less. I appreciate the additional info.

[Adam Griffin]

Well, I thought I'd try my first rough-shot at this without fully understanding all of the components. I'm sure I can do better.

With the requirement of 4 VRA districts, this significantly impacts drawing any Georgia map that adheres to the two characteristics desired above. Furthermore, considering Georgia doesn't actually value municipal boundaries in terms of precinct design more often than not...well, what can you do?

But hey, we don't really value any of that around here. At least I didn't use point contiguity!

Assuming that Georgia is R+6, this map is 8R & 6D, with one of those D districts appearing to be competitive at D+1 (CD11). That's based solely on my familiarity with precinct swings in the northern swing precincts of Fulton & Dekalb, as well as those in portions of Cobb & Gwinnett (it was a D+3 district in 2008, but vast segments of this area at the precinct level saw Romney do 5-6 points better than McCain - among some of the largest swings in the state).

CD3 (which would pit Buddy Carter & Rick Allen against one another) is D+3 but everything else is obviously quite safe. The next closest districts would be Sanford Bishop's CD2 at D+8 and the now-congressmanless CD4 at R+9.

CD2 in particular had to be especially irregular because such is necessary just to get it to 50.2% black VAP. In contrast, the Bishop's real-life 2011 district was only 49.4% black VAP. The other 3 VRA districts are between 54.5% and 56.3% black VAP.

[Adam Griffin]

There are a few helpful tricks in drawing Georgia. For example, DeKalb is the perfect size for one district.

Right. Cobb's another good one, but Dekalb can be used to generate a wholly-contained VRA district. However (and I am not 100% sure about this), putting Dekalb entirely to itself given the nature of white liberals in both Fulton and Dekalb would likely make it very difficult to draw 5 solid D seats + a competitive 6th that wasn't fragmented and snake-like. Additionally, it might wreak havoc on the shape of the other VRA districts.

[Adam Griffin]

There are a few helpful tricks in drawing Georgia. For example, DeKalb is the perfect size for one district.

Right. Cobb's another good one, but Dekalb can be used to generate a wholly-contained VRA district. However (and I am not 100% sure about this), putting Dekalb entirely to itself given the nature of white liberals in both Fulton and Dekalb would likely make it very difficult to draw 5 solid D seats + a competitive 6th that wasn't fragmented and snake-like. Additionally, it might wreak havoc on the shape of the other VRA districts.

So I was wrong about the 5. This is another possibility using Dekalb as its own CD, which does make it possible to generate a comparatively-competitive CD (same numbers for 2008; 54-44 Obama) while maintaining 3 VRA districts in the metro, but that competitive district is a mess in terms of geography.

EDIT: You can tidy it up a bit more on the southern end, but this makes the purple district only 50.3% black VAP.

[Adam Griffin]

I was always curious about SW GA / the current GA-2, because as drawn in 2011 it was 49.5% BVAP. I didn't know if it counted or not, but was curious why GAGOP wouldn't just shatter it if it didn't qualify. I could definitely see it making 2 or more otherwise drawn GOP districts down there potentially "competitive" (in so much as John Barrow's 2011 GA-12 was competitive), but I don't think it'd pose much of a problem. I haven't actually tried drawing a map with GA-2 split up because of that.