Multilevel particle filters: normalizing constant estimation

In this article, we introduce two new estimates of the normalizing constant (or marginal likelihood) for partially observed diffusion (POD) processes, with discrete observations. One estimate is biased but non-negative and the other is unbiased but not almost surely non-negative. Our method uses the multilevel particle filter of Jasra et al. (Multilevel particle lter, arXiv:1510.04977, 2015). We show that, under assumptions, for Euler discretized PODs and a given \(\varepsilon >0\) in order to obtain a mean square error (MSE) of \({\mathcal {O}}(\varepsilon ^2)\) one requires a work of \({\mathcal {O}}(\varepsilon ^{-2.5})\) for our new estimates versus a standard particle filter that requires a work of \({\mathcal {O}}(\varepsilon ^{-3})\). Our theoretical results are supported by numerical simulations.     

Does Actor Perspective Matter? A Case Study of Designing Intervention for Small‐Scale Palm Oil Production Enterprises in Kwaebibirem District of Ghana

Despite the fact that the government of Ghana imports the bulk of its industrial palm oil needs, it still fails to give assistance to about 80 percent of small‐scale producers to enhance development in the industry. To design interventions that will be sustainable for and beneficial to these producers, it is important to understand their perspectives first, so as not to “fix development” for them. This case study in the Kwaebibirem District of Ghana uses an actor‐oriented approach to understand the dynamics in the palm oil enterprise (kramer). Improvements in the kramer evidently evolve from the actors’ own agency. Any intervention for development should therefore first understand the dynamics of the kramer as a social field, and take this perspective as a bottom‐up starting point. This article is divided into six sections; the first section is an introduction, while the second describes our methodology. We next outline our conceptual approach, followed by an analysis of experiences of actors and their interactions. We then describe the resource flows and their interrelationships, including the power relations at play in the kramer networks. Finally, we conclude by drawing lessons on the relevance of an actor perspective in designing a learning intervention for processors, scientists, and extensionists.     

Preventive Impacts of Group Homes in Higher Income Neighborhoods: Retrospective Cohort of Youths in Ontario Group Home Care, 2012 to 2016

Child and Adolescent Social Work Journal - Conduct problem is an ongoing concern among youth placed in group homes. The concern could sometimes become more challenging due to negative peer...     

The Effect of Women’s Empowerment in Agriculture on Household Nutrition and Food Poverty in Northern Ghana

The study examines the effect of women’s empowerment in agriculture on household nutrition—i.e. the availability of carbohydrates, protein, and fat—and household food poverty measured by monetary food shortfall. The analysis is done by applying instrumental variable estimation to a sample of 2642 households from a 2012 population-based survey conducted in northern Ghana. Overall, the results indicate that women’s empowerment positively influences nutrient availability and negatively influences monetary food shortfall. By decomposing women’s empowerment into its component domains, this study identified that the domains of Income, Production, and Leadership are areas for intervention to influence households’ nutrient availability and monetary food shortfall outcomes. The effect of the Time and Resources domains reveal that some intra-household trade-offs may exist. Thus, policies aimed at empowering women to ultimately improve household nutrition and food poverty need to be based on the understanding of these specific interactions.     

Correction to: Multilevel particle filters for Lévy-driven stochastic differential equations

Statistics and Computing - The article Multilevel particle filters for Lévy-driven stochastic differential equations, written by Ajay Jasra, Kody J. H. Law, Prince Peprah Osei, was originally...     

Multilevel particle filters for Lévy-driven stochastic differential equations

Statistics and Computing - We develop algorithms for computing expectations with respect to the laws of models associated to stochastic differential equations driven by pure Lévy processes. We...     

Overcoming interruptions in educational trajectories: Youth in Ghana with international migrant parents

Literature on the effects of parental migration on the education of children who stay at origin, what we call ‘stayer’ youth, mainly focuses on educational outcomes without looking at the process leading to such outcomes. This article addresses this gap by showing how the educational trajectories of stayer youth unfold. Stayer youth may encounter a range of obstacles and interruptions to their education when their parents move overseas, and we explore the agency these youth exert and the support networks they activate to try to overcome them. We employ a youth-centric methodology, based on 15 months of ethnographic fieldwork in three cities in Ghana, with young people whose parents migrated internationally. We find that frequent changes in residence, limited financial means, and lack of academic support cause interruptions in educational trajectories. In response, the young people mobilize support from local social networks to compensate for what they lack from their transnational connections.