This Gist has a couple of things going on, I’ll just list them:
- It downloads the entire history of U.S. House DW-NOMINATE scores from voteview.com
- It evaluates aggregate statistics, with members grouped by party and congress, with easy weighted functions from Hmisc.
- It does the aggregating and data.frame conversion all in one very easy step, using plyr. I have always done this type of aggregation in other ways (by(), *apply(), etc.), but plyr sure made it easy.
- It makes a really pretty nice plot of the distribution of first-dimension ideological ideal points, by party, over time.