Today's Useful Data: Gerrymandering 101

Since Gerrymandering Tuesday is coming up (when the Supreme Court will hear the Wisconsin case), it's time to get clear on what gerrymandering is and how it can conceivably be fixed. I recommend two articles, "Slaying the Partisan Gerrymander" by Sam Wang and Brian Remlinger and "The New Front in the Gerrymandering Wars: Democracy vs. Math" by Emily Bazelon which together make a good, basic primer on gerrymandering and anti-gerrymandering methodologies. Don't know what the "partisan symmetry test" is? You should know about this and also the "efficiency gap" and other relevant measures. These articles will get you up to speed.

Sam Wang's group, the Princeton Gerrymandering Project, also has a very nice site where you can look at particular states and run tests yourself to see the level of gerrymandering under different metrics.

How bad is the problem? Opinions vary, but here's an assessment from the Wang and Remlinger article:

Some analysts claim that Democrats have been at a disadvantage not because of redistricting but because their voters are more clustered geographically. But that geographic pattern does not fully explain Democrats’ recent electoral disadvantage. On the basis of clustering alone, Democrats need to win the national popular vote for the House of Representatives by two percentage points to have an even chance of winning a majority of the seats. But since 2012, gerrymandering has increased the necessary national margin for Democrats to about eight percentage points. In individual gerrymandered states such as North Carolina or Pennsylvania, Democrats need to win by 15 percentage points or more to have a shot at taking a majority.

This is, to say the least, quite unfair and fundamentally anti-democratic. Let's hope the Supremes (we're looking at you, Justice Kennedy) decide to start pushing things back toward a more level playing field.