Social Science Statistics Blog

« Redistricting and Electoral Competition: Part I | Main | Beyond Standard Errors, Part II: What Makes an Inference Prone to Survive Rosenbaum-Type Sensitivity Tests? »

16 December 2005

Redistricting and Electoral Competition: Part II

John Friedman and guest blogger Richard Holden

Yesterday, we blogged about whether gerrymandering or something else a principal cause of low turnover in the House of Representatives and other elected bodies. We continue that discussion today.

How can we determine whether gerrymandering is the culprit, given that any number of reasons could account for the increase in the incumbent reelection rate? The key is that redistricting usually happens only once each decade (at least until the recent controversies in Texas.) Other factors, such as money or electoral polarization, tend to change more smoothly over time. One can tease these factors apart with a
"regression discontinuity" approach, separating the time series into 1) a smooth function and 2) jumps at the time of gerrymandering.

In a recent paper (available at here), we find that redistricting has actually slightly reduced incumbent reelection rates over time. We also look to see if there are systematic differences between "bipartisan" gerrymanders, designed to protect incumbents from both parties, and "partisan" gerrymanders, in which one party attempts to leverage its support into more representation in the state's Congressional delegation. There is no evidence that the incumbent reelection rate responds differently after any of these forms of redistricting.

This research suggests that factors other than redistricting are the more important culprits in today's lack of electoral competition. In some sense, this isn't all that surprising. While the technology available has become more advanced, so have the constraints on gerrymanderers. Supreme Court decisions interpreting the 14th amendment and the Voting Rights Act have consistently narrowed the bounds within which redistricting must occur.

There may, of course, be other reasons to support independent commissions. For instance, they tend to create more geographically compact districts. Neutral bodies also help to avoid the most extreme cases of partisan gerrymandering, in which the neighborhood of an incumbent is grouped with distant voters in a tortuously shaped district. Perhaps most importantly, independent commissions may be able to ensure minority representation - though the Voting Rights Act also plays a fundamental role in this area.

The basic premise of supporters of non-partisan commissions - that political competition is important - is a sound one. But the evidence suggests that these advocates are focused in the wrong place. The redistricting process is far from the only cause of limited competition.

To increase competition in elections for Congress and state legislatures, we must pay more attention to other potential causes of the increase in the incumbent reelection rate. We must better understand how factors such as money, television, and candidate quality impact elections. But if we can direct towards these aspects of democracy the same spirit of reform that now supports the drive towards independent redistricting commissions, new and more promising solutions can't be far away.

Posted by James Greiner at December 16, 2005 2:53 AM