Exit polling and racial bloc voting: Combining individual-level and R×\timesC ecological data

Despite its shortcomings, cross-level or ecological inference remains a necessary part of some areas of quantitative inference, including in United States voting rights litigation. Ecological inference suffers from a lack of identification that, most agree, is best addressed by incorporating individual-level data into the model. In this paper we test the limits of such an incorporation by attempting it in the context of drawing inferences about racial voting patterns using a combination of an exit poll and precinct-level ecological data; accurate information about racial voting patterns is needed to assess triggers in voting rights laws that can determine the composition of United States legislative bodies. Specifically, we extend and study a hybrid model that addresses two-way tables of arbitrary dimension. We apply the hybrid model to an exit poll we administered in the City of Boston in 2008. Using the resulting data as well as simulation, we compare the performance of a pure ecological estimator, pure survey estimators using various sampling schemes and our hybrid. We conclude that the hybrid estimator offers substantial benefits by enabling substantive inferences about voting patterns not practicably available without its use.Comment: Published in at http://dx.doi.org/10.1214/10-AOAS353 the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org

The Scythe Statistical Library: An Open Source C++ Library for Statistical Computation

The Scythe Statistical Library is an open source C++ library for statistical computation. It includes a suite of matrix manipulation functions, a suite of pseudo-random number generators, and a suite of numerical optimization routines. Programs written using Scythe are generally much faster than those written in commonly used interpreted languages, such as R and \proglang{MATLAB}; and can be compiled on any system with the GNU GCC compiler (and perhaps with other C++ compilers). One of the primary design goals of the Scythe developers has been ease of use for non-expert C++ programmers. Ease of use is provided through three primary mechanisms: (1) operator and function over-loading, (2) numerous pre-fabricated utility functions, and (3) clear documentation and example programs. Additionally, Scythe is quite flexible and entirely extensible because the source code is available to all users under the GNU General Public License.

MCMCpack: Markov Chain Monte Carlo in R

We introduce MCMCpack, an R package that contains functions to perform Bayesian inference using posterior simulation for a number of statistical models. In addition to code that can be used to fit commonly used models, MCMCpack also contains some useful utility functions, including some additional density functions and pseudo-random number generators for statistical distributions, a general purpose Metropolis sampling algorithm, and tools for visualization.

A Micro-level Analysis of Recent Increases in Labor Force Participation among Older Workers

Aggregate data reveal a sizable increase in labor force participation rates since 2000 among workers on the cusp of retirement, reverting back to levels for older men not seen since the 1970s. These aggregate numbers are useful in that they document overall trends, but they lack the ability to identify the reasons behind workers’ decisions. The Health and Retirement Study (HRS) spans the last dozen years from 1992 to 2004, includes two cohorts of retirees, and provides micro-level data regarding these recent trends. Moreover, the HRS contains information on older Americans and the types of jobs they are taking (full-time versus part-time, self-employed versus wage-and-salary, low-paying versus high-paying, blue collar versus white collar, etc.). This study capitalizes on the richness of the HRS data and explores labor force determinants and outcomes of older Americans, with an emphasis on retirees' choices in recent years. We present a cross-sectional and longitudinal description of the financial, health, and employment situation of older Americans. We then explore retirement determinants using a multinomial approach to model gradual retirement and a two-step approach to model the work-leisure and hours intensity decisions of older workers. Evidence suggests that the majority of older Americans retire gradually, in stages, and that younger retirees continue to respond to financial incentives just as their predecessors did. In addition, recent macro-level changes appear to have blurred the distinction between younger and middle-aged retirees.Economics of Aging, Partial Retirement, Gradual Retirement

An Update on Bridge Jobs: The HRS War Babies

Are today’s youngest retirees following in the footsteps of their older peers with respect to gradual retirement? Recent evidence from the Health and Retirement Study (HRS) suggests that most older Americans with full-time career jobs later in life transitioned to another job prior to complete labor force withdrawal. This paper explores the retirement patterns of a younger cohort of individuals from the HRS known as the “War Babies.” These survey respondents were born between 1942 and 1947 and were 57 to 62 years of age at the time of their fourth bi-annual HRS interview in 2004. We compare the War Babies to an older cohort of HRS respondents and find that, for the most part, the War Babies have followed the gradual-retirement trends of their slightly older predecessors. Traditional one-time, permanent retirements appear to be fading, a sign that the impact of changes in the retirement income landscape since the 1980s continues to unfold.Economics of Aging, Partial Retirement, Gradual Retirement

The Role of Re-entry in the Retirement Process

To what extent do older Americans re-enter the labor force after an initial exit and what drives these “unretirement” decisions? Retirement for most older Americans with full-time career jobs is not a one-time, permanent event. Labor force exit is more likely to be a process. Prior studies have found that between one half and two thirds of career workers take at least one other job before exiting from the labor force completely. The transitional nature of retirement may be even more pronounced when considering the impact of re-entry. This paper examines the extent to which older Americans with career jobs re-entered the labor force. The analysis is based on data from the Health and Retirement Study (HRS), an ongoing, longitudinal survey of older Americans that began in 1992. We examined the retirement patterns of a subset of 5,617 HRS respondents who were on a full-time career job at the time of the first interview. Logistic regression was used to explore determinants of re-entry among those who initially exited the labor force. We found that approximately 15 percent of older Americans with career jobs returned to the labor force after initially exiting. Respondents were more likely to re-enter if they were younger, were in better health, or had a defined-contribution pension plan. This research provides empirical evidence of how older Americans are utilizing bridge jobs as they transition from career employment, and that re-entry may be an important part of the work experience of older Americans.Economics of Aging, Partial Retirement, Bridge Jobs, Gradual Retirement

Self-Employment Transitions among Older American Workers with Career Jobs

What role does self-employment play in the retirement process? Older Americans are staying in the labor force longer than prior trends would have predicted and many change jobs later in life. These job transitions are often within the same occupation or across occupations within wage-and-salary employment. The transition can also be out of wage-and-salary work and into self employment. Indeed, national statistics show that self employment becomes more prevalent with age, partly because self employment provides older workers with opportunities not found in traditional wage-and-salary jobs, such as flexibility in hours worked and independence. This paper analyzes transitions into and out of self employment among older workers who have had career jobs. We utilize the Health and Retirement Study, a nationally-representative dataset of older Americans, to investigate the prevalence of self employment among older workers who made a job transition later in life and to explore the factors that determine the choice of wage-and-salary employment or self employment. We find that post-career transitions into and out of self employment are common and that health status, career occupation, and financial variables are important determinants of these transitions. As older Americans and the country as a whole face financial strains in retirement income in the years ahead, self employment may be a vital part of the pro-work solution.Retirement, Retirement Transitions, Self Employment

Assessing Preference Change on the U.S. Supreme Court

The foundation upon which accounts of policy-motivated behavior of Supreme Court justices are built consists of assumptions about the policy preferences of the justices. To date, most scholars have assumed that the policy positions of Supreme Court justices remain consistent throughout the course of their careers and most measures of judicial ideology—such as Segal and Cover scores—are time invariant. On its face, this assumption is reasonable; Supreme Court justices serve with life tenure and are typically appointed after serving in other political or judicial roles. However, it is also possible that the worldviews, and thus the policy positions, of justices evolve through the course of their careers. In this article we use a Bayesian dynamic ideal point model to investigate preference change on the US Supreme Court. The model allows for justices’ ideal points to change over time in a smooth fashion. We focus our attention on the 16 justices who served for 10 or more terms and completed their service between the 1937 and 2003 terms. The results are striking—14 of these 16 justices exhibit significant preference change. This has profound implications for the use of time-invariant preference measures in applied work.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/116217/1/jleo07a.pd

Applied Bayesian Inference in R using MCMCpack

http://deepblue.lib.umich.edu/bitstream/2027.42/116223/1/rnews06.pd

The `Rehnquist’ Court (?)

http://deepblue.lib.umich.edu/bitstream/2027.42/116263/1/lawcourt05.pd