Tuesday, January 10, 2017

Adjusted ADA scores from 1947-2015

Below you will find updated Americans for Democratic Action (ADA) scores covering the period 1947 to 2015 (the latest available). They are based upon ADA scores of selected congressional vote records independently tabulated by Groseclose, Levitt, and Snyder (1999) (for 1947-1998 originally and later extended by Groseclose to 2008) and Anderson and Habel (2009) (for 1947-2007), and have been updated and reconciled by myself (2008-2015). They are adjusted using the improved procedure from Dr. Groseclose, still based upon his original paper.

The final (adjusted) data are based upon the Anderson collection (mainly because when I started work that was what I had accessible). I correct over 150 mislabeled records that do not match valid ICPSR records as maintained by Keith Poole (as augmented with preliminary records for the 114th congress). Errors were often due to changes in seats, especially to people with similar names, or changes in party of the congressmen.

For the period 1990-2008, I additionally hand-corrected all discrepancies between the Anderson and Groseclose data. In some cases, records were missing from one source or the other. In others the scores were incorrectly transcribed or identifying data were incorrect. In a few cases the source data were ambiguous - in some years a score is provided even if the member served for less than half the eligible votes and occasionally the score does not match the recorded votes. Where possible, I trust the recorded votes over the scores, and omit any congressmen ineligible or deceased for more than half the votes. I also generally counted absences the same as negative votes, even if the congressman served a partial term (since this is ADA's general practice), although for 2007-2015 I omitted anyone who missed more than 6 votes (as I learned this was the practice of Groseclose et al.). There were around 380 such discrepancies and 150+ corrections. Given this work, the period since 1990 can be trusted to be of high accuracy. Earlier data still have discrepancies, and data prior to 1972 show a large number of discrepancies, which I highlight in the excel files provided below. These seem to largely be due to different policies for how to treat votes in years before a numerical score was assigned by ADA. I leave further correction / homogenization for future work.

I calculate the scores using two base years for the adjustment -- 1980 (as used in both the above papers), and 1999 (as used as the Political Quotient [PQ] in Dr. Groseclose's book Left Turn, which he chose because empirically that base year gives the average congressman in the 2000's an adjusted score near 50). If you would prefer a different base year, the code to produce it is below as well.


Adjusted scores with 1980 base year (.xlsx file)
Adjusted scores with 1999 base year (.xlsx file)
Raw data and code to reproduce (including raw output files and parameters) (.zip file)

Citations: The original papers above.

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