POLI 100B CONGRESS
2 February 2006

  1. The Spatial (Geometric) Model of Voting and Party Competition: Theory

    1. Assumptions:

      1. Legislators have Symmetric Single-Peaked Utility functions centered on their ideal points in the Policy Space.

      2. Legislators vote for the Policy Outcome Closest to them

    2. The number of Policy Dimensions needed to account for roll call voting in a Legislature is usually only 1 or 2 because of Constraint.

      Philip E. Converse, "The Nature of Belief Systems in Mass Publics," 1964

      • "A term like "ideology" has been thoroughly muddied by diverse uses. We shall depend instead upon the term "belief systems" ... We define a belief system as a configuration of ideas and attitudes in which the elements are bound together by some form of constraint or functional interdependence." (p.207)

      • Constraint Does Not Have to be Strictly Logical - "…few belief systems of any range at all depend for their constraint upon [strict] logic in this classical sense. … What is important is that the elites familiar with the total shapes of these belief systems have experienced them as logically constrained clusters of ideas, within which one part necessarily follows from another." (p.210-211)

      • From an observer's point of view, constraint means that certain issue positions are bundled together, and the knowledge of one or two issue positions makes the remaining positions very predictable.

    3. Roll Call Voting on One Basic Dimension -- How Issue Mappings Occur



    4. Roll Call Voting on Two Basic Dimensions -- How Issue Mappings Occur



  2. Estimating Spatial (Geometric) Maps of Voting and Party Competition

    1. Driving Distances Between Cities

                   ATLANTA BOISE BSTN  CHIC  CINN DALLAS DENV   LA  MIAMI   WDC CASBS

ATLANTA        0000  2340  1084   715   481   826  1519  2252   662   641  2450
BOISE          2340  0000  2797  1789  2018  1661   891   908  2974  2480   680
BOSTON         1084  2797  0000   976   853  1868  2008  3130  1547   443  3160
CHICAGO         715  1789   976  0000   301   936  1017  2189  1386   696  2200
CINCINNATI      481  2018   853   301  0000   988  1245  2292  1143   498  2330
DALLAS          826  1661  1868   936   988  0000   797  1431  1394  1414  1720
DENVER         1519   891  2008  1017  1245   797  0000  1189  2126  1707  1290
LOS ANGELES    2252   908  3130  2189  2292  1431  1189  0000  2885  2754   370
MIAMI           662  2974  1547  1386  1143  1394  2126  2885  0000  1096  3110
WASHINGTON      641  2480   443   696   498  1414  1707  2754  1096  0000  2870
CASBS          2450   680  3160  2200  2330  1720  1290   370  3110  2870  0000


    2. Multidimensional Scaling (MDS) Map From Driving Distances



    3. Agreement Scores Between Members of Congress

      90th Senate (1967-68) Agreement Scores

      108th Senate (2003-04) Agreement Scores

    4. Multidimensional Scaling (MDS) Map From 90th Senate Agreement Scores



    5. Driving Distances as an Unfolding Problem

                   HOUSTON     NYC   ORLANDO  PORTLAND  ST LOUIS  SAN DIEGO

ATLANTA         790      850      430     2660      570     2150
BOISE          1820     2490     2640      430     1670      980
BOSTON         1830      210     1300     3140     1210     2880
CHICAGO        1090      810     1150     2120      290     2090
CINCINNATI     1150      470     1000     2430      320     2290
DALLAS          250     1560     1100     2040      660     1350
DENVER         1030     1790     1880     1260      860     1100
LOS ANGELES    1540     2790     2430      960     1840      130
MIAMI          1190     1330      230     3260     1230     2680
WASHINGTON     1370      240      850     2780      860     2600
CASBS          1890     2960     2850      670     2150      490
    6. MDS Map From an Unfolding Analysis of Driving Distances



    7. Roll Call Voting as an Unfolding Problem



    8. A Spatial (Geometric) Model of Roll Call Voting

      1. Each Legislator is represented by an ideal point and has a symmetric, single-peaked utility function centered at her ideal point over the policy space.

      2. Each Roll Call Vote is represented by Two points
        -- One Corresponding to the Yea Outcome -- Oy
        -- and One Corresponding to the Nay Outcome -- On.

      3. Legislators vote Probabilistically for the closest outcome:

        Probability of Yea = P[U(Oy) > U(On)]
        Probability of Nay = P[U(Oy) < U(On)]


    9. Spatial (Geometric) Map From 90th Senate Unfolding of Roll Call Votes



    10. Roll Call Voting in the Supreme Court
      Rehnquist   11116111111161111111611116611111111111111111111111616116111161116111161111111111111161111111116111111111111111611111161101111111611111111111116116111161611116666111111111111116111111111111661111116111611111111111611161111111111111111111111111111161111111111161111111116161110111161111116161611161111111111111111111111161161116111111111111111161111111116111111111611111111111111111111611116116111611111161111111111111111111116111110111111111111116111111166111116611111116111111611111111161611616111111111116111116
Stevens     61111116111116166611116111160111161111111116661116111161611111161111116611616111111616616111661166666661116111111111111106116616161611061111161111661116161111111111111111101661661616616666111611111611161111661611111611161611111611116611111111111611616116166611111166111111116166116161661616111611161616611111161111611111611661161161611111111116116116111611111116111116111661611111611116661161161161116111611111111611111116661111110111111111166611666661111666161111111611116116116166161111111111166616666661666661
OConnor     11116111111161111611111611111161111116111161111111161111111161116111111111111111661116111111161111111111111111111111111101111111111111611161111111111161111111116111111111111111616111111111161111111111116111111116111161111111111111111111111116111111111111161111111111116611111111111611111111166011111111111111111111111111111111116161111111111111111111111111111111611111111111116111111111111106111611661161111111111111111111116111110110111111111116111111116111116111111111111111111111611111111116111161111111111111
Scalia      11116161111111111016611116611111611116111111111111616111111116116111111111111111111161111116116111111111111161111111661101111111611111111161116116111161611116661161111111111116111111111111666116611111116111111116616161111111116111111111161166111111111111111161111111611611111111161611116161616161111111111111111111111111111116116111111111111161116111116116111111616611111161116111111611116116116611661161666111111111611111111111110111111161111116111111161116116611111111111111611111111661111616111111111116111116
Kennedy     11111111111111111111611111111111111111111111111111116116111116111111111111111111111111111116611111111111111111111111111101111111611111161111116116111116111111111111111111161111111111111111111111161111111111111111111611111111116611111111111161111111111111111111111111111111111111111111116161116111111111111111111111111161161111111111111111111661111111111111111111111111111111111111111111111111111611111111111111111111111111111111110111111111111161111111166111111111111111111111616111611111611611611111111111111111
Souter      11111111111111116111111111111111111116111111111111161161611161111111111611611111161166611111661116611661111111111111111101111111110611161111161111161111111111111111111111111661661616111111111111111111111111111111111111111111111111111111111111111111616116111111111116111111111111116161661611661111111611111161111111111161111611111161111111111111116111111111161116111116111111111111111611161111166161116611611111111611111116111111110166111611111111111111111111161111111111111111111111111611111111661611111611666111
Thomas      11116661111161111616611116611111611616111111111111116116111116116116161111111111661161111116116111111111111611611111661106111111611111111161116116111161611116666611111111111111111111111111660116611111116111111116611161111111116111111111111166111111111111111161111111611611111111161611116161616161111111111111111111111111111116116111111111111161111111116116111111616611111661116111111111111116116111611161166111111111611111111111610111111161111166111111161111116611111116111111611111111161111666111111111116111116
Ginsburg    11111110111116111111111111111111661111111111161116111111611111111111111611611111111111611111611166666661111111111111111101111111111611111111161111161111111111611111111111161661161616111161111611166611111111611111111111111111111111111111111116111111616111166161111166116111111116116161661616111111111611111111111111611111661611111111111111111111116111111611161116111116111111111111111611166111161161116116611111111666111116111111110161111111110111111111111111161111611111116111116111666611611111166611111611666111
Breyer      11111111111166111111111111110161611111111166111111161111611111161111111610601111111116610111111116616661111161111111111101111611101111661111161111111111111111111111111111111661666616611111111111111111661111611111111111111111111111111611161111111111116111166611111166116161111116116161661611161611161616111161111111111111611661111161111111111111111111111611161116111111111611611111111116661111161161166116111111611166111116116111110661111111111111611111116111111111611111111111116111160111111111161666166661666611
      The Configuration below accounts for 96.95 percent of 2,624 total choices on 263 non-unanimous decisions.



      Below is a plot of the cutting lines for the 263 non-unanimous decisions. The red arrows indicate the predicted majority side (Oy) for the corresponding cutting line. The Blue dots are the 9 justices.



    11. The 88th (1963-64) U.S. Senate -- Final Passage of the 1964 Civil Rights Act



    12. The 108th (2003-04) U.S. Senate









    13. The 109th (2003-04) U.S. Senate

    14. The Ideological Structure of Congressional Voting

    15. Animated GIF of Congresses 1 - 107

    16. The 80th (1947-48) Congress US Map (Blue = Democrat, Red = Republican)



    17. The 100th (1987-88) Congress US Map (Red = Democrat, Blue = Republican)



    18. The 2000 Presidential Election





    19. The 2004 Presidential Election



  3. The Polarization of American Politics

    1. The 93rd versus the 108th House



    2. House Party Means on the First Dimension 1879 - 2004



    3. House Party Means on the Second Dimension 1879 - 2004



    4. House and Senate Polarization 1879 - 2004



    5. House and Senate Party Unity Scores 1879 - 2004