Climate shocks and migration: an agent-based modeling approach

This is a study of migration responses to climate shocks. We construct an agent-based model that incorporates dynamic linkages between demographic behaviors, such as migration, marriage, and births, and agriculture and land use, which depend on rainfall patterns. The rules and parameterization of our model are empirically derived from qualitative and quantitative analyses of a well-studied demographic field site, Nang Rong district, northeast Thailand. With this model, we simulate patterns of migration under four weather regimes in a rice economy: (1) a reference, “normal” scenario; (2) 7 years of unusually wet weather; (3) 7 years of unusually dry weather; and (4) 7 years of extremely variable weather. Results show relatively small impacts on migration. Experiments with the model show that existing high migration rates and strong selection factors, which are unaffected by climate change, are likely responsible for the weak migration response.     

Productivity drift in extended learning curves

The pattern of changes in the Extended Learning Curves representing the performance of 114 assembly workers in an electronics firm is examined in terms of changes in productivity drift over long periods of time. It is shown that 2 types of discontinuities can occur. The first consists of a temporary levelling off in productivity followed by a recovery to new higher levels of productivity; the second has a sustained period of negative productivity drift. A number of work facets are statistically tested as possible causes of these patterns of productivity drift, but, the only significant relationship (at P ≤ 0.05 level) is with length of service in job. Some evidence is presented to show that conventional work measurement methods are not effective in terms of assessing the true work output of experienced workers since such workers are able to beat the system by claiming those allowances which are most difficult to cross-check.     

Geographic information systems, spatial network analysis, and contraceptive choice

How does family planning accessibility affect contraceptive choice? In this paper we use techniques of spatial analysis to develop measures of family planning accessibility, and evaluate the effects of these geographically derived measures in a multilevel statistical model of temporary method choice in Nang Rong, Thailand. In our analyses we combine spatial data obtained from maps and Global Positioning System (GPS) readings with sociodemographic data from surveys and administrative records. The new measures reveal (1) important travel time effects even when family planning outlets are close by; (2) independent effects of road composition; (3) the relevance of alternative sources of family planning supply; and (4) the importance of the local history of program placement.     

Population responses to environmental change: looking back,looking forward

Population and Environment - Over the past two decades, population researchers have engaged in a far-reaching and productive program of research on demographic responses to changes in the natural...     

A production engineering approach to robot selection

The successful introduction of robots into an industrial enterprise means real commitment, engineering support, and detailed involvement in the planning of an integrated manufacturing system. In particular, the production engineer is clearly seen in this context to be the system designer. He must therefore be in a position to specify the performance of all man and machine components within the system such that productivity is maximised. Robot types are reviewed, and analogies between man and machine are used to introduce the RTM concept. Finally, a simple method is given for estimating robot throughput times from elementary velocity profiles. The fall-off in throughput due to the effect of many small robot movements is emphasised.     

Migrant remittances and the web of family obligations: ongoing support among spatially extended kin in North-east Thailand, 1984-94

Exchanges of money, goods, and assistance among family/kin members are influenced by the intertwined lives of individuals and their family/kin. As people pass through the young adulthood years, acquiring obligations as spouses and parents, and migrating in search of economic opportunities, tensions can arise over existing obligations. Using rich longitudinal data from Northeast Thailand, we examined the role of family networks (origin and destination) on migrants' exchanges with family/kin. Our approach overcame many shortcomings of earlier studies, allowing us to 'see' the family social network arrayed in a broader network. We show that intra-family exchanges are influenced by marital status, the presence of children, having parents in the origin household, and having siblings depart from it. The results are stable across sensitivity tests that systematically include or exclude various familial links. In addition, reports provided by origin households on migrant remittances are consistent with reports from migrants themselves.     

Work Patterns Following a Birth in Urban and Rural China: A Longitudinal Study

Two waves of data (1989 and 1991) from theChina Health and Nutrition Survey (CHNS) areused to investigate the short-term impact of abirth on women's work patterns. Defining workbroadly in terms of involvement inincome-earning activities in general, birthshave little impact. Defining work in terms ofwage employment, births have a significantalthough modest negative effect. Substituting amore fully elaborated typology of work patternsthat distinguishes different combinations ofwage work, work in household businesses, andagricultural fieldwork makes it possible tolook at shifts within as well as betweencategories of wage and non-wage employment.These shifts turn out to be important,especially in rural areas where such workpredominates. In this study, the effect of abirth depends on how work is conceptualized andmeasured. Some of the contextual variability inthe strength of the fertility-work relationshipreported in the literature may be due to theparticular measures of work that have beenused, which better reflect the time demands,intensity, flexibility, and location of work inurban industrialized settings than in rural,less industrialized ones.