Michael Bailey (Georgetown--Govt.) has updated the Bridge Ideal Points estimates (click here) to cover years 1950 through 2020. These Ideal point estimates include the Supreme Court, presidential, and congressional ideology estimates and are designed to facilitate inter-institutional and cross-temporal comparisons.
While the Bridge Ideal Points compete somewhat with the Martin-Quinn scores in the literature, the two sets of ideology estimates correlate reasonably highly with one another. Despite the overlap, these two ideology estimates differ in two important ways.First, "Bridge Ideal Points are designed to be intertemporally comparable. Martin and Quinn scores assume the ideological cutpoints of Supreme Court cases are drawn from a common distribution across years, which makes them less comparable across time when the case load changes." Second, while Martin and Quinn scores only cover the Supreme Court justices, Bridge Ideal Points for justices are comparable to Bridge Ideal Points for presidents and members of Congress as well.
Regardless of one's preference, efforts to estimate justice ideology remain a staple in the judicial decisionmaking literature.
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