938Numerical methods for determining leadership and ideology in Congress
- Dec 26, 2010Longer version here:
Today I am publishing two new types of statistics for understanding the
behavioral relationships between Members of Congress. The first is a new
approach to a leader-follower score, based on the same algorithm Google
uses to rank pages on the web. The second statistic is an update to my
political spectrum graph. New charts are presented at the end (attached).
New Leadership Scores
The first new statistic I am publishing today involves a completely new
type of analysis of congressional behavior. The inspiration for this
analysis comes from Google’s PageRank algorithm, which governs how
Google ranks the order of pages in its search results. Google’s method
is widely known: the more links you get, the higher ranked your page but
links you get from highly ranked pages are even better.
In Congress, we can look at the network of who is cosponsoring whose
bills. When a representative cosponsors a bill, it is a vote of
confidence not only for that bill but also a vote of confidence or
loyalty for the bill’s sponsor. If we imagine Members of Congress each
as a “web page” and each time a Member cosponsors another Member’s bill
it is a link from one “web page” to that of the other, then the PageRank
algorithm is going to reveal the ranking of the implicit loyalties
directly from the public, official behavior of the Members of Congress.
The results of this Congressional PageRank-style Leadership Analysis run
over the last two years of sponsorship data look roughly good. In the
Senate, the highest value is given to Harry Reid, the Majority Leader.
The Minority Leader, Mitch McConnell, has nearly the highest value among
the Republicans. In the House, the leadership values are overall
relatively low for the Speaker, party leaders, and party whips. I could
only guess about why the Senate and House have this difference. One of
the lowest values in the House was given to little-known Rep. Chakka
Fattah (PA-2), my former congressman, though famous recently for his
unique idea of replacing the income tax with a transaction tax.
This is a new approach to the leader-follower scores I published a few
years ago, which came directly out a suggestion from Joseph Barillari
(who I knew in college). The idea behind a leader-follower score is that
if I cosponsor your bills but you do not cosponsor my bills, then I am a
follower relative to you being a leader.
New Political Spectrum
The first large-scale statistical analysis I did on legislative data —
my 2004 political spectrum — was in the language of statistics a
principle components analysis of something like a term-document matrix.
The idea is that Members of Congress (“terms”) who cosponsor similar
sets of bills (“documents”) should be grouped together, while Members of
Congress who don’t cosponsor any of the same bills should be grouped far
apart. The process doesn’t look at the content of the bills or the party
affiliation or anything else about the Members of Congress, but it is
able to infer underlying behavioral patterns, some of which correspond
to real-world concepts like left-right ideology. In the new version of
my political spectrum, the "documents" are also Members of Congress.
(See the blog post for details.)
Well finally here are some graphics. Each chart attached is a
scatterplot of Members of Congress. The x-axis is the political spectrum
value from the new method (oriented with Democrats on the left, color
indicates party for reference). The y-axis is the new Leadership score.
In other words, we’d expect Democratic leaders to be in the top left;
GOP leaders in the top right; GOP followers in the bottom-right; and so
on. The first chart is for the Senate, the second for the House.
I’ve additionally labeled in green the leadership positions in the
Senate and House so you can easily locate those folks. Again, it seems
to work well in the Senate, not so much in the House.
I've omitted why I think these charts are interesting and important to
be able to produce --- I doubt that's in question. But, of course, this
all wouldn't have been made possible without bulk legislative data
which, as we all know, Congress does NOT provide.
I'd be interested in any thoughts you have on why the images look the
way they do, such as why the House leadership ranks so low?
- Josh Tauberer
- CivicImpulse / GovTrack.us
http://razor.occams.info | www.govtrack.us | civicimpulse.com
"Members of both sides are reminded not to use guests of the
House as props."
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