gov3009-l February 2009

gov3009-l@lists.fas.harvard.edu

1 participants
4 discussions

Richardson on ``Analysis of the Binary Instrumental Variable Model"

by Justin Grimmer

Dear Applied Statistics Community, Please join us this Wednesday, when Thomas Richardson--Department of Statistics, University of Washington--will present "Analysis of the Binary Instrumental Variable Model", work that is joint with Jamie Robins, Harvard School of Public Health. Thomas provided the following abstract: In this talk I consider an instrumental variable potential outcomes model in which the instrument (Z), treatment (X) and response (Y) are all binary. It is well known that this model is not identified by the observed joint distribution p(x,y,z). Consequently many statistical analyses impose additional untestable assumptions or change the causal estimand of interest. Here we take a different approach, directly characterizing and graphically displaying the set of distributions over potential outcomes that correspond to a given population distribution p(x,y,z). This provides insights into the variation dependence between the partially identified average causal effects for various compliance groups. The analysis also leads directly to re-parametrization that may be used for Bayesian inference and the development of models that incorporate baseline covariates. The Applied Statistics Workshop meets each Wednesday at 12 noon in K-354 CGIS-Knafel (1737 Cambridge St). The workshop begins with a light lunch and presentations usually start around 1215 and last until about 130 pm. Cheers Justin Grimmer

15 years, 2 months

Garip presenting "How Do Network Externalities Lead to Intergroup Inequality?"

by Justin Grimmer

Dear Applied Statistics Community, Please join us this Wednesday when Filiz Garip, Harvard Department of Sociology, will present here joint-work with Paul Dimaggio, "How Do Network Externalities Lead to Intergroup Inequality?". Filiz provided the following abstract for her talk: In this paper, we identify a mechanism, which we contend chronically reproduces and, under some conditions, may generate or even efface intergroup inequality. That mechanism is (a) the diffusion of goods, services, and practices that (b) are characterized by strong network externalities under conditions of (c) social homophily. When the value of a good or practice to an agent is a function of the number of persons in that agent's network who also possess the good or engage in the practice, and when networks are homophilic with respect to certain social characteristics, this mechanism will exacerbate initial individual-level differences in access to the good or practice and, under some conditions, induce persistent intergroup inequality. We illustrate this claim in two empirical contexts. For the first, the diffusion of access to and use of the Internet, we start with observed data on the relationship between cost and adoption and between adoption levels and price, and produce a computational model that permits us to predict variation in intergroup inequality over time as a function of variation in the strength of network externalities and the extent of social homophily. For the second, the practice of rural-to-urban migration by young people in rural Thailand, we use village-level data on family resources and migration patterns to explore the relationship between information sharing, homophily, and intergroup differences in migration. The Applied Statistics Workshop meets each Wednesday at 12 noon in K-354 CGIS-Knafel (1737 Cambridge St). The workshop begins with a light lunch and presentations usually start around 1215 and last until about 130 pm. Hope you can make it Cheers Justin Grimmer

15 years, 2 months

Western on "Analyzing inequality with Variance Function Regressions"

by Justin Grimmer

Dear Applied Statistics Community, Please join us this Wednesday, February 11th when Bruce Western, Professor of Sociology, will present "Analyzing Inequality with Variance Function Regressions". Bruce provided the following abstract: Regression-based studies of inequality model only between-group differences, yet often these differences are far exceeded by residual inequality. Residual inequality is usually attributed to measurement error or the influence of unobserved characteristics. We present a regression that includes covariates for both the mean and variance of a dependent variable. In this model, the residual variance is treated as a target for analysis. We apply this model to study the effects of union membership decline on the growth in men's earnings inequality from 1970 to 2006. The union membership data offer additional challenge for data analysis, because survey respondents may misreport their union membership status. The Applied Statistics Workshop meets each Wednesday at 12 noon in K-354 CGIS-Knafel (1737 Cambridge St). The workshop begins with a light lunch and presentations usually start around 1215 and last until about 130 pm. Hope to see you at the workshop, Justin Grimmer

15 years, 2 months

Lok on "Bayesian Combination of State Polls and Election Forecasts"

by Justin Grimmer

Dear Applied Statistics Community, The first meeting of the applied statistics workshop will be this Wednesday, February 4th, when Kari Lock, Graduate Student in the Department of Statistics, will present "Bayesian Combination of State Polls and Election Forecasts". Kari provided the following abstract: A wide range of potentially useful data are available for election forecasting: the results of previous elections, a multitude of pre-election polls, and predictors such as measures of national and statewide economic performance. How accurate are different forecasts? We estimate predictive uncertainty via analysis of data collected from past elections (actual outcomes, pre-election polls, and model estimates). With these estimated uncertainties, we use Bayesian inference to integrate the various sources of data to form posterior distributions for the state and national two-party Democratic vote shares for the 2008 election. Our key idea is to separately forecast the national popular vote shares and the relative positions of the states. The Applied Statistics Workshop meets each Wednesday at 12 noon in K-354 CGIS-Knafel (1737 Cambridge St). The workshop begins with a light lunch and presentations usually start around 1215 and last until about 130 pm. Cheers, Justin Grimmer

15 years, 2 months

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gov3009-l February 2009