Senate Voting Analysis and Visualization

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In this case study, we take data from the votes on bills in the US Senate (2004-2006), shown as a table on the left, and explore how we can visualize the data by projecting it, first on a line then on a plane. We investigate how we can choose the line or plane in a way that maximizes the variance in the result, via a principal component analysis method. Finally we examine how a variation on PCA that encourages sparsity of the projection directions allows to understand which bills are most responsible for the variance in the data.

Source: VoteWorld.