In a quick teaser, we tallied all votes taken during the 114th United States Congress and built a score to show how frequently parties tend to vote along their own party lines. For a member of the House of Representatives, the score is merely the number votes with their own party members divided by the number of votes with the opposite party.

A score of 1.000 means that the member of Congress shared as many votes with their own party as outside of their party. A score below 1.000 shows that a member of Congress votes against their party more often. Of the over 450 House bills votes on during the 114th Congress (January 2015 through current), no members of Congress fall below a score of 1.000.

The figure below shows the distribution of Republican scores (red) against the Democrat scores (blue).

For the 253 Republicans, we see that the scores tend to be about 2.5 or higher. This shows that most Republicans tend to share 71% of their votes with Republicans and 29% of their votes with Democrats.

For the 192 Democrats, we see that the scores tends to be between 1 and 2.5. This means that Democrats tends to share between 50% and 71% of their votes with their own party.

Note: Don’t be baffled by the numbers; this is conditional probability. What these plots show are that Democrats tend to cross over an vote with Republicans on certain matters; while Republicans rarely come across to vote with Democrats. A clear example is the following::

Suppose House Resolution 90210 (HR 90210) is put to vote. Suppose the bill is considered a “Pro-Republican” bill. Furthermore suppose that all Republicans vote for the bill; but only 60 of the 192 democrats vote for the bill. Then the resulting score for each republican is 253 / 60 = 4.2167. For Democrats that voted with the Republicans, their score is 0.2372. For the Democrats that voted against the Republicans, their scores are all 132.0000 (denominator is automatically set to 1).

Then for House Resolution 8675309 (HR 8675309) the votes go completely split. All Republicans vote together; all Democrats vote together and against Republicans. Then the scores become the following:

• Republican Scores: (252 + 252) / 60 = 8.4000
• Democrat (who voted with the Republicans) Scores: (60 + 192)/253 = 0.9960
• Democrat (who always opposed Republicans) Scores: (132 + 192)/1 = 324.000

This little example for two bills shows an example of a sect of Democrats never compromising; Republicans not compromising but sharing some ideologies with Democrats; and Democrats who had compromised with Republicans.

More on this in a future post!