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Paper

Do Majority-Minority Districts Maximize Black Representation in Congress Epstein, David O'Halloran, Sharyn Cameron, Charles Uploaded 01-01-1995 Keywords districting voting rights act minority representation electoral systems semi-parametric estimation Abstract This paper investigates the question of whether or not concentrated minority districts, which increase the probability that minorities are elected to office but decrease minority influence elsewhere, maximize overall black representation in Congress. We address this question in a three-step process: we first estimate representation equations that link constituency preferences to the actions of their representative; then electoral equations that link constituency characteristics to the type of representative elected; and finally combine these two effects to simulate the districting strategies that maximize substantive minority representation. We find that outside of the South, dividing minority voters equally across districts maximizes representation, while in the South the optimal scheme creates concentrated districts on the order of 47% black voting age population. We also conclude that minority candidates have substantial chances of being elected from districts with less than 50% minority voters, and that in the face of a national Republican tide, optimal districting schemes will concentrate minority voters less, rather than more.

2

Paper

Covariate Functional Form in Cox Models Keele, Luke Uploaded 10-25-2005 Keywords Cox model event history survival models splines semi-parametric duration models Abstract In most event history models, the effect of a covariate on the hazard is assumed to have a log-linear functional form. For continuous covariates, this assumption is often violated as the effect is highly nonlinear. Assuming a log-linear functional form when the nonlinear form applies causes specification errors leading to erroneous statistical conclusions. Scholars can, instead of ignoring the presence of nonlinear effects, test for such nonlinearity and incorporate it into the model. I review methods to test for and model nonlinear functional forms for covariates in the Cox model. Testing for such nonlinear effects is important since such nonlinearity can appear as nonproportional hazards, but time varying terms will not correct the misspecification. I investigate the consequences of nonlinear function forms using data on international conflicts from 1950-1985. I demonstrate that the conclusions drawn from this data depend on fitting the correct functional form for the covariates.

3

Poster

Weighted Estimation for Analyses with Missing Data Samii, Cyrus Uploaded 07-21-2010 Keywords missing data doubly robust inverse probability weighting semi-parametric post-treatment regression sample selection Abstract Missing data plague data analyses in political science. The recent applied statistics literature reflects renewed interest in weighting methods for missing data problems. Three properties are stressed in this literature: (i) robustness, (ii) the ability to use post-treatment information in causal analysis, and (iii) methods to gain efficiency. I present these results, hoping to show the potential in using refashioned weighting methods for political science research.