Compound impacts from droughts and structural vulnerability on human mobility.

Extreme dry events already disrupt populations' ability to migrate. In a warming climate, compound drought events could amplify vulnerability and drive forced migration. Here, we contribute the first multi-method research design on societal impacts from compound drought events. We show how mobility patterns are shaped by the intersection of drought and social vulnerability factors in three drought-prone countries - Madagascar, Nepal, and Mexico. We find that internal migration in agricultural communities in Mexico increased by 14 to 24 basis points from 1991 to 2018 and will prospectively increase by 2 to 15 basis points in Nepal in case of a compound drought event in 2025. We show that consecutive drought events exacerbate structural vulnerabilities, limiting migrants' adaptation options, including long-range migration. We conclude that the additional social pre-conditions, e.g., social isolation and lack of accurate information, ultimately limit migration as an adaptation option for households vulnerable to compound drought events.

Integrating explanation and prediction in computational social science.

Computational social science is more than just large repositories of digital data and the computational methods needed to construct and analyse them. It also represents a convergence of different fields with different ways of thinking about and doing science. The goal of this Perspective is to provide some clarity around how these approaches differ from one another and to propose how they might be productively integrated. Towards this end we make two contributions. The first is a schema for thinking about research activities along two dimensions-the extent to which work is explanatory, focusing on identifying and estimating causal effects, and the degree of consideration given to testing predictions of outcomes-and how these two priorities can complement, rather than compete with, one another. Our second contribution is to advocate that computational social scientists devote more attention to combining prediction and explanation, which we call integrative modelling, and to outline some practical suggestions for realizing this goal.

Economic Shock and Migration: Differential Economics Effects, Migrant Responses, and Migrant Cumulative Causation in Thailand.

Classic migration theory predicts that individual and household migration decisions are partially responsive to economic pushes from origin communities and pulls from destinations. Recent theorizing argues that this basic relationship is fundamentally influenced by the experiences accumulated within migrant streams, connecting potential migrants with future migrants between origin and destination. Drawing upon a 16-year study of migrant departures and returns from 22 villages in northeastern Thailand, we extend current knowledge about these fundamental relationships before, during, and after Thailand's economic crisis of 1997. We answer the following questions: How are migrant departures from the origin affected by the crisis, how are migrant returns to origin communities affected by the crisis, and how do migrants' accumulated experiences connecting origin and destination moderate these relationships? We examine effects separately for men and women since village and destination economies are sufficiently sex differentiated. We find that migrant selectivity partially explains year effects: that is, earlier periods are more highly selective. Migrant cumulative experiences facilitate migration throughout the time period and modestly influence the migration decisions during economic downturns, but these effects are far more important for women than for men. For return migration, year effects emerge only for the post 1997-98 period and only after controlling for migrant social capital and occupational sector. Origin-based migrant social capital slightly, but significantly, reduces the odds of return migration throughout the period of observation. However, migrant social capital does amplify the likelihood of return migration after the Asian Financial Crisis. Construction workers are the most likely to return to their origin villages after the Asian Financial Crisis, while manufacturing, service, and agricultural workers show little change in behavior.

Who donates their bodies to science? The combined role of gender and migration status among California whole-body donors.

The number of human cadavers available for medical research and training, as well as organ transplantation, is limited. Researchers disagree about how to increase the number of whole-body bequeathals, citing a shortage of donations from the one group perceived as most likely to donate from attitudinal survey data - educated white males over 65. This focus on survey data, however, suffers from two main limitations: First, it reveals little about individuals' actual registration or donation behavior. Second, past studies' reliance on average survey measures may have concealed variation within the donor population. To address these shortcomings, we employ cluster analysis on all whole-body donors' data from the Universities of California at Davis, Irvine, Los Angeles, and San Francisco. Two donor groups emerge from the analyses: One is made of slightly younger, educated, married individuals, an overwhelming portion of whom are U.S.-born and have U.S.-born parents, while the second includes mostly older, separated women with some college education, a relatively higher share of whom are foreign-born and have foreign-born parents. Our results demonstrate the presence of additional donor groups within and beyond the group of educated and elderly white males previously assumed to be most likely to donate. More broadly, our results suggest how the intersectional nature of donors' demographics - in particular, gender and migration status - shapes the configuration of the donor pool, signaling new ways to possibly increase donations.

The impact of migration and remittances on wealth accumulation and distribution in rural Thailand.

This article studies the impact of internal migration and remittance flows on wealth accumulation and distribution in 51 rural villages in Nang Rong, Thailand. Using data from 5,449 households, the study constructs indices of household productive and consumer assets with principal component analysis. The changes in these indices from 1994 to 2000 are modeled as a function of households' prior migration and remittance behavior with ordinary least squares, matching, and instrumental variable methods. The findings show that rich households lose productive assets with migration, potentially because of a reduction in the labor force available to maintain local economic activities, while poor households gain productive assets. Regardless of wealth status, households do not gain or lose consumer assets with migration or remittances. These results suggest an equalizing effect of migration and remittances on wealth distribution in rural Thailand.

Individuals' decision to co-donate or donate alone: an archival study of married whole body donors in Hawaii.

BACKGROUND: Human cadavers are crucial to numerous aspects of health care, including initial and continuing training of medical doctors and advancement of medical research. Concerns have periodically been raised about the limited number of whole body donations. Little is known, however, about a unique form of donation, namely co-donations or instances when married individuals decide to register at the same time as their spouse as whole body donors. Our study aims to determine the extent of whole body co-donation and individual factors that might influence co-donation. METHODS AND FINDINGS: We reviewed all records of registrants to the University of Hawaii Medical School's whole body donation program from 1967 through 2006 to identify married registrants. We then examined the 806 married individuals' characteristics to understand their decision to register alone or with their spouse. We found that married individuals who registered at the same time as their spouse accounted for 38.2 percent of married registrants. Sex differences provided an initial lens to understand co-donation. Wives were more likely to co-donate than to register alone (p = 0.002). Moreover, registrants' main occupational background had a significant effect on co-donations (p = 0.001). Married registrants (regardless of sex) in female-gendered occupations were more likely to co-donate than to donate alone (p = 0.014). Female-gendered occupations were defined as ones in which women represented more than 55 percent of the workforce (e.g., preschool teachers). Thus, variations in donors' occupational backgrounds explained co-donation above and beyond sex differences. CONCLUSIONS: Efforts to secure whole body donations have historically focused on individual donations regardless of donors' marital status. More attention needs to be paid, however, to co-donations since they represent a non-trivial number of total donations. Also, targeted outreach efforts to male and female members of female-gendered occupations might prove a successful way to increase donations through co-donations.

Repeat migration and remittances as mechanisms for wealth inequality in 119 communities from the Mexican Migration Project data.

To evaluate the distributional impact of remittances in origin communities, prior research studied how migrants' selectivity by wealth varies with migration prevalence in the community or prior migration experience of the individual. This study considers both patterns; it examines selectivity separately in low- and high-prevalence communities and for first-time and repeat migrants. Based on data from 18,042 household heads in 119 Mexican communities from the Mexican Migration Project, the analyses show that (1) first-time migrants in low-prevalence communities come from poor households, whereas repeat migrants in high-prevalence communities belong to wealthy households; and (2) higher amounts of remittances reach wealthy households. These results suggest that repeat migration and remittances may be mechanisms for wealth accumulation in the study communities. Descriptive analyses associate these mechanisms with increasing wealth disparities between households with and without migrants, especially in high-prevalence communities. The study, similar to prior findings, shows the importance of repeat migration trips, which, given sustained remittances, may amplify the wealth gap between migrants and nonmigrants in migrant-sending communities. The study also qualifies prior findings by differentiating between low- and high-prevalence communities and observing a growing wealth gap only in the latter.

Increasing Migration, Diverging Communities: Changing Character of Migrant Streams in Rural Thailand.

This paper studies how increasing migration changes the character of migrant streams in sending communities. Cumulative causation theory posits that past migration patterns determine future flows, as prior migrants provide resources, influence, or normative pressures that make individuals more likely to migrate. The theory implies exponentially increasing migration flows that are decreasingly selective. Recent research identifies heterogeneity in the cumulative patterns and selectivity of migration in communities. We propose that this heterogeneity may be explained by individuals' differential access to previously accumulated migration experience. Multi-level, longitudinal data from 22 rural Thai communities allow us to measure the distribution of past experience as a proxy for its accessibility to community members. We find that migration becomes a less-selective process as migration experience accumulates, and migrants become increasingly diverse in socio-demographic characteristics. Yet, selectivity within migrant streams persists if migration experience is not uniformly distributed among, and hence not equally accessible to, all community members. The results confirm that the accumulation and distribution of prior migrants' experiences distinctly shape future migration flows, and may lead to diverging cumulative patterns in communities over time.

Social capital and migration: how do similar resources lead to divergent outcomes?

This article investigates how migrant social capital differentially influences individuals 'migration and cumulatively generates divergent outcomes for communities. To combine the fragmented findings in the literature, the article proposes a framework that decomposes migrant social capital into resources (information about or assistance with migration), sources (prior migrants), and recipients (potential migrants). Analysis of multilevel and longitudinal data from 22 rural villages in Thailand shows that the probability of internal migration increases with the available resources, yet the magnitude of increase depends on recipients' characteristics and the strength of their ties to sources. Specifically, individuals become more likely to migrate if migrant social capital resources are greater and more accessible. The diversity of resources by occupation increases the likelihood of migration, while diversity by destination inhibits it. Resources from weakly tied sources, such as village members, have a higher effect on migration than resources from strongly tied sources in the household. Finally, the importance of resources for migration declines with recipients' own migration experience. These findings challenge the mainstream account of migrant social capital as a uniform resource that generates similar migration outcomes for different groups of individuals or in different settings. In Nang Rong villages, depending on the configuration of resources, sources, and recipients, migrant social capital leads to differential migration outcomes for individuals and divergent cumulative migration patterns in communities.

Mapping Gender and Migration in Sociological Scholarship: Is It Segregation or Integration?

A review of the sociological research about gender and migration shows the substantial ways in which gender fundamentally organizes the social relations and structures influencing the causes and consequences of migration. Yet, although a significant sociological research has emerged on gender and migration in the last three decades, studies are not evenly distributed across the discipline. In this article, we map the recent intellectual history of gender and migration in the field of sociology and then systematically assess the extent to which studies on engendering migration have appeared in four widely read journals of sociology (American Journal of Sociology, American Sociological Review, Demography, and Social Forces). We follow with a discussion of these studies, and in our conclusions, we consider how future gender and migration scholarship in sociology might evolve more equitably.

Gendered Migrant Social Capital: Evidence from Thailand.

Employing longitudinal data from Thailand to replicate studies of cumulative causation, we extend current knowledge by measuring frequency of trips, duration of time away, level of network aggregation (village or household), and sex composition of migrant networks to estimate a model of prospective migration among men and women in Thailand. We find that trips and duration of time away have distinct influences upon migration; that household level migrant networks are more influential than village level migrant networks; that female migrant networks and male migrant networks have different influences upon migration outcomes; and, that migrant social capital influences men and women's migration differently. Our elaboration provides significant quantitative evidence as to how gender and family variously imbue migration dynamics.