Abstract
Abstract
In this article, I introduce a new index for measuring partisan bias called the Directional Proportionality Index (DPIx) and apply it to elections to the House of Representatives since 1900. Derived from the Loosemore-Hanby index, the novelty of DPIx lies in the fact that it synthesizes a proportionality index with a measure of partisan symmetry. I then apply this index to House elections from 1900 to 2016 at the national level as well as in several states, and I also tested it against hypothetical circumstances in which the negative effects of gerrymandering are completely eliminated. The results demonstrate that while gerrymandering is currently producing a pro-Republican bias, this asymmetrical disproportionality has regularly existed in House elections over the past century and was often much more severe. The evidence suggests that short of substantial electoral reform, asymmetrical disproportionality is likely to remain a fundamental characteristic of American electoral politics.
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