Glossary

Post Summary:This is a glossary of some of the specialized terms used in The Majority Line.


Votes In Agreement (VIA) - The number of Votes In Agreement for a particular member is generated by a Monte Carlo simulation of a theoretical roll call vote using the percentage of past agreement as an estimate of the probability of agreement of the vote. The number of simulated votes is set at 100. The standard error in the mean is usually plus or minus 1-2 votes, so we take it as best estimated as plus or minus 2 votes. In other words, the Votes In Agreement is really a mean that we have 95% confidence is in the range of that mean plus or minus two votes. The roll call vote is theoretical because it takes place among all the members who had voted in that chamber for that Congress. Bear in mind that the probability of agreement of a member who replaced that member is zero.

Chamber - either the United States House of Representatives or the United States Senate.

VIA Index - The VIA Index is the VIA normalized to the number of members of the chamber. We will treat it as a percentage. Theoretically the VIA Index could exceed 100% in certain cases, though that circumstance is not a practical concern. Each VIA Index technically consists of a range of a 95% confidence interval, due to the standard error in computing the mean VIA. We don't display that information, though a reader should keep in mind that two members that differ by a point or two in their VIA Index are likely equivalent in their ability to attract the same, or close to the same, number of voters in agreement in any particular simulated roll call vote.

Majority Points - A Majority Point is computed by taking a particular members vote in a particular roll call, and first assigning a Yea vote as value of 1, a Nay vote a value of -1, and any other type of vote (Present, Not Voting, someone's name, etc.) as 0. Then a value for the roll call is assigned as 1 if the Yeas were greater than the Nays, -1 if the Nays were greater than the Yeas, and 0 otherwise (ties). These two numbers are then multiplied, giving either a value of 1 - if the member voted in the group with the larger number of Yea/Nay votes, -1 - if the member voted in the group with the smaller number of Yea/Nay votes, 0 - if either they didn't vote or no majority was established (a tie vote gives all the voting members a Majority Point of zero).

Majority Index - The Majority Index is the sum of a member's Majority Points divided by the number of votes that member particpated in, multiplied by 100. It can theoretically be in the range of -100 to 100.

Relationship Matrix

Unity Index - the total sum of Majority Points across all members of a chamber, normalized by the total number of possible Majority Points for that chamber in that Congress. The total number of possible Majority Points is the number of members of a chamber times the number of votes. We will treat it as a percentage. There is a discrepency in the House for those years where the traditionally non-voting members (e.g. Puerto Rico's Resident Commissioner) were allowed to participate in some roll call votes. Theoretically the Unity Index could exceed 100% for those years, though that is not a practical concern.

Opposition Index - The percentage of the chamber that is part of the Opposition.

The Majority Line - The Majority Line is set at the larger of (i) the value of the Majority Index for which there would be just over fifty percent of the chamber (fifty percent - rounded down - plus one more member) who have voted in 85% or more of the votes, (ii) zero. The Majority Line is rarely set at zero, except in those cases where many of the members with positive Majority Index voted in less than 85% of the votes (e.g. the Senate of the 4th Congress).

Opposition - The Opposition comprises those members of a chamber with negative Majority Index. There may, or may not, be an Opposition for any particular chamber in any particular Congress.

Majority - The Majority comprises all members with non-negative Majority Index, except those below The Majority Line.

Minority - The Minority comprises all members with non-negative Majority Index, except those at or above the Majority Line. There may, or may not, be a Minority for any particular chamber in any particular Congress.

Significant number of votes - A significant number of votes is at least 85% of the votes taken in a particular chamber in a particular Congress. Requiring that a member participate in a significant number of votes is used to filter some members out of the network diagram showing the agreement relationship between members (the "Red" and Green" diagrams).

Significant participation- Significant participation in the voting is voting either Yea or Nay (or their equivalent) in is at least 65% of the votes taken in a particular chamber in a particular Congress. Significant participation is the requirement for a member to be listed on the leaderboard.