Senate voting data matrix.
The data consists of the votes of Senators in the 2004-2006 US Senate (2004-2006), for a total of bills. “Yay” (“Yes”) votes are represented as 1‘s, “Nay” (“No”) as -1‘s, and the other votes are recorded as 0. (A number of complexities are ignored here, such as the possibility of pairing the votes.)
This data can be represented here as a ‘‘voting’’ matrix
with elements taken from . Each column of the voting matrix contains the votes of a single Senator for all the bills; each row contains the votes of all Senators on a particular bill.