Senatorial decision making: I. The determination of structure

A three-mode factor analysis of the U. S. Senate roll call voting was performed. The modes were: issues, time and Senator seats. The entries into the data matrix were the point biserial correlations of a Senator's votes on a particular issue in a particular time period with the popularity of the roll calls in that set. Five Senator factors were found, indicating the various voting coalitions. There were indications of the ideological, geographic and partisan structure within the Senate. There was also the formulation of the factors of time change which indicate how coalitions vary across time.