Land Ownership as a Determinant of Temporary Migration in Nang Rong, Thailand

In this study I consider landownership as a determinant of temporary migrationin a rural area of Thailand. Previous researchon rural areas in developing countries hasfocused on the use of migration to diversifyhousehold incomes across economic sectors andacross geographic areas. I combine thisliterature with economic theories of migrationto understand the effect of land ownership ontemporary migration of household members inNang Rong, Thailand. I estimate regressionmodels predicting the probability of ahousehold having any temporary migrants, andpredicting the number of male or femaletemporary migrants in the household. I findthat households with smaller landholdings arediversifying through migration in order tosupplement rural income, while households withlarger landholdings are diversifying in orderto overcome the absence of accessible credit inthe village.     

A modified false discovery rate multiple-comparisons procedure for discrete data, applied to human immunodeficiency virus genetics

Summary.  To help to design vaccines for acquired immune deficiency syndrome that protect broadly against many genetic variants of the human immunodeficiency virus, the mutation rates at 118 positions in HIV amino-acid sequences of subtype C versus those of subtype B were compared. The false discovery rate (FDR) multiple-comparisons procedure can be used to determine statistical significance. When the test statistics have discrete distributions, the FDR procedure can be made more powerful by a simple modification. The paper develops a modified FDR procedure for discrete data and applies it to the human immunodeficiency virus data. The new procedure detects 15 positions with significantly different mutation rates compared with 11 that are detected by the original FDR method. Simulations delineate conditions under which the modified FDR procedure confers large gains in power over the original technique. In general FDR adjustment methods can be improved for discrete data by incorporating the modification proposed.     

Poor Mothers and Habits of Hiding: Participatory Methods in Poverty Research

Poor mothers have long‐standing habits of hiding their lives in response to punitive authorities and stigma. We identify practices of hiding daily life, and we describe participatory research approaches for and ethical concerns in learning more about poor women's critical insights and survival strategies.     

Composition-consistent tournament solutions and social choice functions

This paper introduces a new axiom for choice in preference profiles and tournaments, called composition-consistency. A social choice function is composition-consistent if it is non-sensitive to the cloning of one or several outcomes. The key feature of the composition consistency property is an operation concept called multiple composition product of profiles. The paper provides a brief overview of some social choice functions studied in the literature. Concerning the tournament solutions, it is proved that the Top Cycle, the Slater and the Copeland solutions are not composition-consistent, whereas the Banks, Uncovered Set, TEQ, Minimal Covering Set are composition-consistent. Moreover, we define the composition-consistent hull of a solution as the smallest composition-consistent solution containing . The composition-consistent hulls of the Top cycle and Copeland solutions are specified, and we give some hints about the location of the hull of the Slater set. Concerning social choice functions, it is shown that Kemeny, Borda and Minimax social choice functions are not composition-consistent, whereas the Paretian one is composition-consistent. Moreover, we prove that the latter is the composition-consistent hull of the Borda and Minimax functions.     

THE EFFECTS OF INTERDISCIPLINARY EDUCATIONAL FORMATS ON CONCEPT RETENTION AND PROBLEM–SOLVING ABILITY*

The purpose of this study was to examine the effects of different interdisciplinary problem-oriented formats on a student's knowledge of and retention of disciplinary concepts and principles, his application of these concepts and principles to disciplinary problems, and his use of a discipline in his analysis of a complex problem. Performances of students enrolled in the experimental sections were compared to those of students enrolled in standard lecture-discussion sections. Regression analysis was used to analyze students' performance in order to control the effects of differences in student backgrounds. It was found that altering the pedagogical format and reward system within the experimental sections had no significant effect upon student performances in the experimental, problem-oriented program. In general, this study indicates that students taught in the standard lecture-discussion format in which grades are determined by examination over course material retain concepts and principles, apply these concepts and principles to disciplinary problems, and integrate disciplinary concepts into their analysis of complex problems as well as, if not better than, students taught in an interdisciplinary, problem-solving format.     

Perceived social standing among Asian immigrants in the US: Do reasons for immigration matter?

We investigate the association between a subjective measure of social status and the reasons for immigration among Asian immigrants in the US. We use data from the National Latino and Asian American Study to test several hypotheses about this association. Our analyses show the positive effect on perceived social standing of migrating for better education, the negative effect of migrating to seek employment, and the negative impact of refugee status. Migrating for family reunification can be associated with various circumstances, which lead to differing outcomes. The results suggest that the notion that immigrants arrive in the US with limited resources and few skills and move slowly up the socioeconomic ladder must be reassessed in light of the complex social context and factors such as ethnicity, gender, divergent immigration paths, and a range of associated circumstances.     

Joint modeling of longitudinal and survival data with the Cox model and two-phase sampling

A common objective of cohort studies and clinical trials is to assess time-varying longitudinal continuous biomarkers as correlates of the instantaneous hazard of a study endpoint. We consider the setting where the biomarkers are measured in a designed sub-sample (i.e., case-cohort or two-phase sampling design), as is normative for prevention trials. We address this problem via joint models, with underlying biomarker trajectories characterized by a random effects model and their relationship with instantaneous risk characterized by a Cox model. For estimation and inference we extend the conditional score method of Tsiatis and Davidian (Biometrika 88(2):447–458, 2001) to accommodate the two-phase biomarker sampling design using augmented inverse probability weighting with nonparametric kernel regression. We present theoretical properties of the proposed estimators and finite-sample properties derived through simulations, and illustrate the methods with application to the AIDS Clinical Trials Group 175 antiretroviral therapy trial. We discuss how the methods are useful for evaluating a Prentice surrogate endpoint, mediation, and for generating hypotheses about biological mechanisms of treatment efficacy.     

Emergency Saving and Household Hardship

Households with limited income and wealth often struggle to access the financial liquidity needed to address unexpected expenses or income drops. Emergency savings can act as form of insurance against such economic shocks and reduce the risk of hardships that influence family wellbeing. Prior research has established that threshold amounts of liquid assets can reduce the risk of economic hardship. This study used a measure of self-reported emergency saving behavior to examine whether households who reported saving for emergencies were less likely to experience subsequent economic hardships in a longitudinal sample of households in disadvantaged neighborhoods from the Annie E. Casey Foundation’s Making Connections project. Results across a range of regression models suggest that households who saved for emergencies experienced slightly less overall hardship and were less likely to report several specific hardships, such as food insecurity and having a phone disconnected, three years later. This study supports the idea that small, unrestricted savings may play a protective role for low-income households.