Nathalie E. Williams

Design of an Agent-Based Model to Examine Population-Environment Interactions in Nang Rong District, Thailand

The design of an Agent-Based Model (ABM) is described that integrates Social and Land Use Modules to examine population-environment interactions in a former agricultural frontier in Northeastern Thailand. The ABM is used to assess household income and wealth derived from agricultural production of lowland, rain-fed paddy rice and upland field crops in Nang Rong District as well as remittances returned to the household from family migrants who are engaged in off-farm employment in urban destinations. The ABM is supported by a longitudinal social survey of nearly 10,000 households, a deep satellite image time-series of land use change trajectories, multi-thematic social and ecological data organized within a GIS, and a suite of software modules that integrate data derived from an agricultural cropping system model (DSSAT - Decision Support for Agrotechnology Transfer) and a land suitability model (MAXENT - Maximum Entropy), in addition to multi-dimensional demographic survey data of individuals and households. The primary modules of the ABM are the Initialization Module, Migration Module, Assets Module, Land Suitability Module, Crop Yield Module, Fertilizer Module, and the Land Use Change Decision Module. The architecture of the ABM is described relative to module function and connectivity through uni-directional or bi-directional links. In general, the Social Modules simulate changes in human population and social networks, as well as changes in population migration and household assets, whereas the Land Use Modules simulate changes in land use types, land suitability, and crop yields. We emphasize the description of the Land Use Modules - the algorithms and interactions between the modules are described relative to the project goals of assessing household income and wealth relative to shifts in land use patterns, household demographics, population migration, social networks, and agricultural activities that collectively occur within a marginalized environment that is subjected to a suite of endogenous and exogenous dynamics.

Measures of Human Mobility Using Mobile Phone Records Enhanced with GIS Data

In the past decade, large scale mobile phone data have become available for the study of human movement patterns. These data hold an immense promise for understanding human behavior on a vast scale, and with a precision and accuracy never before possible with censuses, surveys or other existing data collection techniques. There is already a significant body of literature that has made key inroads into understanding human mobility using this exciting new data source, and there have been several different measures of mobility used. However, existing mobile phone based mobility measures are inconsistent, inaccurate, and confounded with social characteristics of local context. New measures would best be developed immediately as they will influence future studies of mobility using mobile phone data. In this article, we do exactly this. We discuss problems with existing mobile phone based measures of mobility and describe new methods for measuring mobility that address these concerns. Our measures of mobility, which incorporate both mobile phone records and detailed GIS data, are designed to address the spatial nature of human mobility, to remain independent of social characteristics of context, and to be comparable across geographic regions and time. We also contribute a discussion of the variety of uses for these new measures in developing a better understanding of how human mobility influences micro-level human behaviors and well-being, and macro-level social organization and change.

Spatiotemporal Detection of Unusual Human Population Behavior Using Mobile Phone Data

With the aim to contribute to humanitarian response to disasters and violent events, scientists have proposed the development of analytical tools that could identify emergency events in real-time, using mobile phone data. The assumption is that dramatic and discrete changes in behavior, measured with mobile phone data, will indicate extreme events. In this study, we propose an efficient system for spatiotemporal detection of behavioral anomalies from mobile phone data and compare sites with behavioral anomalies to an extensive database of emergency and non-emergency events in Rwanda. Our methodology successfully captures anomalous behavioral patterns associated with a broad range of events, from religious and official holidays to earthquakes, floods, violence against civilians and protests. Our results suggest that human behavioral responses to extreme events are complex and multi-dimensional, including extreme increases and decreases in both calling and movement behaviors. We also find significant temporal and spatial variance in responses to extreme events. Our behavioral anomaly detection system and extensive discussion of results are a significant contribution to the long-term project of creating an effective real-time event detection system with mobile phone data and we discuss the implications of our findings for future research to this end.

Overlooked potential: older-age parents in the era of ART.

Abstract The advent of widespread ART provision in low- and middle-income countries requires not just medical attention, but also social and psychological support to encourage and monitor strict adherence to drug regimens. Developing innovative approaches to providing this broad support is a major challenge, especially within the financial constraints of resource-limited countries hardest hit by the epidemic. In this study, we examine the role of older-age parents in monitoring ART treatment and caring for their HIV-infected children and grandchildren in Cambodia. Our results are based on 25 open-ended interviews with older-age parents of people with AIDS (PWHA). A high level of co-residence when PWHA become ill and a sense of parental responsibility and emotional attachment facilitate high parental involvement in their childrens and grandchildrens illness, care and treatment. Our interviews indicate that parents play an important role in encouraging their children to get tested and to access treatment if they test positive. They consistently monitor antiretroviral therapy (ART) adherence and opportunistic infections and remind PWHA to attend medical appointments and support-group meetings. Parents also provide for the nutrition and hygiene of PWHA essential to the success of ART treatments. We find that despite low levels of education, older parents were able to express clear, correct and detailed knowledge of complicated ART treatment regimens, nutrition and hygiene. Overall, our findings show that older parents play a pivotal role in care and treatment if they are provided with proper resources and training and have the ability to understand the necessity and details of ensuring strict adherence to medications. Based on these results, we suggest that explicitly including older parents in policy and programs for care and treatment would allow Cambodia and other countries to take advantage of this unique and effective but overlooked asset in AIDS care and treatment.

Gender, traumatic events, and mental health disorders in a rural Asian setting

Research shows a strong association between traumatic life experience and mental health and important gender differences in that relationship in the western European Diaspora; but much less is known about these relationships in other settings. We investigate these relationships in a poor rural Asian setting that recently experienced a decade-long armed conflict. We use data from 400 adult interviews in rural Nepal. The measures come from World Mental Health survey instruments clinically validated for this study population to measure depression, posttraumatic stress disorder, and intermittent explosive disorder. Our results demonstrate that traumatic life experience significantly increases the likelihood of mental health disorders in this setting, and that these traumatic experiences have a larger effect on the mental health of women than men. These findings offer important clues regarding the potential mechanisms producing gender differences in mental health in many settings.

How community organizations moderate the effect of armed conflict on migration in Nepal.

This study analyses micro-level variability in migration during armed conflict in Nepal. The analysis is based on a multi-dimensional model of individual out-migration that examines the economic, social, and political consequences of conflict and how community organizations condition the experience of these consequences and systematically alter migration patterns. Detailed data on violent events and individual behaviour during the Maoist insurrection in Nepal and multi-level event-history analysis were used to test the model. The results indicate that community organizations reduced the effect of conflict on out-migration by providing resources that helped people cope with danger, as well as with the economic, social, and political consequences of the conflict. The evidence suggests that the conflict caused the population to be systematically redistributed in a way that will probably affect its future socio-demographic composition—the extent of the redistribution depending on the resources available in each community.

Migrant Values and Beliefs: How Are They Different and How Do They Change?

This is a study of the values of migrants. We examine processes of selection—how values affect migration—and adaptation—how migration influences value changes. Empirical analyses use a unique collection of data that combines detailed information on values from a representative sample of non-migrants in Nepal with a representative sample of Nepali migrants living in the Persian Gulf. Results suggest that migrants were selected from those who were more materialistic, less committed to religion and more family-oriented. In terms of adaptation, our results are consistent with the idea that migrants become more religious, less committed to historical Nepali values, and change ideas about family-orientation in mixed ways. Thus, we find that value adaptations of migrants are complex processes that could have immense impacts on ideational diffusion around the world.

Community Reaction to Older Age Parental AIDS Caregivers and Their Families: Evidence From Cambodia

Accounts of community reactions to persons with HIV/AIDS and their families typically focus only on negative reactions stemming from stigmatization, with little acknowledgement of variation over time and across settings. To usefully guide local interventions, a broader view is needed that also encompasses attitudes and actions stemming from sympathy and friendship. The authors examined community reactions in Cambodia to families from the perspectives of parents of adults who died of AIDS or currently receive antiretroviral therapy. Survey evidence and open-ended interviews revealed a mixture of reactions with respect to social relations, interactions with local officials, gossip, business patronage, funeral participation, and orphaned grandchildren. Positive support was often dominant, and reactions typically improved substantially over time. Misplaced fears of contagion through casual contact underlay most negative reactions. Moral condemnation or blame was not evident as a source of negative reactions. Overall, a sufficiently supportive atmosphere likely exists in many localities to facilitate community-based efforts to mitigate the epidemic’s impact on affected families.

HIV/AIDS and Older Persons: Shifting the Focus From the Infected to the Affected

More than a decade ago, the November 1998 issue of Research on Aging (ROA) was devoted to the topic of HIV/AIDS and aging and stood out as one of the rare serious attempts to bring older persons into the discourse concerning the epidemic. It was preceded by an edited volume on the topic published almost a decade earlier (Riley, Ory, and Zablotsky 1989) and followed by a theme issue on the topic in June 2003 of JAIDS (Journal of Acquired Immune Deficiency Syndromes). All three collections were very welcome given the scant attention that was being paid to older persons in the context of HIV/ AIDS. However, each focused almost exclusively on the situation in the United States and on older persons who were either infected or at risk of infection with HIV. Although together the ROA and JAIDS theme issues included 37 articles, only one in each dealt explicitly with the situation outside North America and only these same articles discussed consequences for older persons who were affected rather than infected by the disease (Knodel, Watkins, and VanLandingham 2003; Sankar et al. 1998). This limited focus leaves open the need for research on older persons in relation to the epidemic in settings outside the United States who, even though not infected themselves, may be affected by the illness and death of others who are. The reality of the epidemic is that in 2007 only 4% of persons living with HIV worldwide and 1% of the deaths were in North America. In contrast, two thirds of the HIV caseload was in sub–Saharan Africa and

Using Survey Data for Agent-Based Modeling: Design and Challenges in a Model of Armed Conflict and Population Change

Although agent-based models (ABMs) have become more commonly found in the demographic literature in the past decade, the use of survey data to populate and operationalize ABMs is still rare in demography. This technique, more commonly found in the geographic and land use literature, creates opportunities to study entirely new questions, but is time-consuming and cumbersome to use. In this chapter, we seek to contribute to the use of survey data based ABMs for demographic purposes. We do this by presenting details of the design, structure, and functioning of an agent-based model we created to examine the influence of armed conflict on population composition and change. In addition to presenting our model design, we also discuss several challenges and solutions to using survey data in the initialization and parameterization of survey-data based ABMs. Finally, we present illustrative examples from our ABM and compare the results with regression-based analyses. It is our aim that this presentation and discussion will expedite the design and testing of ABMs for future projects.