[caption id=”attachment_45150″ align=”aligncenter” width=”4272″]File
[/caption]
President Obama and many leading Democrats are publicly complaining that Republicans have created a polarized political environment which prevents them from accomplishing necessary business, like immigration reform and Obamacare. But according to the analysis of L.J. Zigerell, a political scientist writing for the Washington Post, the reverse is true. Over the past 30 years, Democrats have been tacking to the left much more rapidly than Republicans have been tilting right.
Zirerell notes that some political commentators, use something called a DW-Nominate score to plot this chart which seems to show a more rapid polarization by Republicans. A statistician’s dream, this score attempts to define ideology as two-dimensional by placing ideologically similar legislators closer to each other and distancing them along the axis from ideologically different legislators.
The trouble? This method of gauging ideology follows Congressional role call votes. It is effective for gauging the polarity of a given Congress, but loses its effectiveness when the timeline is extended.
Zigerell offered an alternative means of showing ideological shift, which “provide[d] ideology estimates for members of congress based on donations to and from each member” since 1980. These results showed a clearly different trend.
Which is the better graph? Zigerell is hesitant to say.
“It is not that one technique is superior to the others,” he writes. “But one technique may be more useful for some purposes and the other technique more useful for other purposes.”
However, for the non-statisticians among us, the take away is Zigerell’s final graph, which demonstrates that Democrats have become increasingly tied monetarily to leftist groups and that this trend has been accelerating over the course of roughly the last decade. Political polarization is real, but it is far less balanced than DCCC fundraising emails would have one believe.
