研究

我是一位方法論學者,專注於複雜系統和統計計算的交叉領域,重點關注高性能計算和機器學習。我工作的核心部分是開發科學軟件:作為一名專業軟件工程師,我投入大量精力確保我創建的方法和工具可靠、開放,並且研究社區可以廣泛使用。我的合作涵蓋多個領域,包括流行病學、公共衛生、社交網絡分析和基因組學,但它們都有一個共同的基礎——密集計算和先進的統計方法。

若要查看完整且持續更新的出版物索引,請參閱 Google Scholar 個人資料。您也可以透過 ORCIDGitHub軟體頁面 追蹤相關研究與程式。

引用数据来自 OpenAlex,下载量来自 CRAN。更新于 2026-08-15。

  • 无日期进行中

    Generalized Machine Learning for Fast Calibration of Agent-Based Epidemic Models

    Najafzadehkhoei, S., Vega Yon, G. G., Modenesi, B., & Meyer, D. S.

    摘要

    Agent-based models (ABMs) are widely used to study infectious disease dynamics, but their calibration is often computationally intensive, limiting their applicability in time-sensitive public health settings. We propose DeepIMC (Deep Inverse Mapping Calibration), a machine learning-based calibration framework that directly learns the inverse mapping from epidemic time series to epidemiological parameters. DeepIMC trains a bidirectional Long Short-Term Memory (BiLSTM) neural network on synthetic epidemic trajectories generated from agent-based models such as the Susceptible-Infected-Recovered (SIR) model, enabling rapid parameter estimation without repeated simulation at inference time. We evaluate DeepIMC through an extensive simulation study comprising 5,000 heterogeneous epidemic scenarios and benchmark its performance against Approximate Bayesian Computation (ABC) using likelihood-free Markov Chain Monte Carlo. The results show that DeepIMC substantially improves parameter recovery accuracy, produces sharp and well-calibrated predictive intervals, and reduces computational time by more than an order of magnitude relative to ABC. Although structural parameter identifiability constraints limit the precise recovery of all model parameters simultaneously, the calibrated models reliably reproduce epidemic trajectories and support accurate forward prediction with their estimated parameters. DeepIMC is implemented in the open-source R package epiworldRCalibrate, facilitating practical adoption for real-time epidemic modeling and policy analysis. Overall, our findings demonstrate that DeepIMC provides a scalable, operationally effective alternative to traditional simulation-based calibration methods for agent-based epidemic models.

  • 2026进行中

    Hidden Burden of a Measles Outbreak Revealed by Genomic and Transmission Models

    Marye, A., Toth, D. J. A., Vega Yon, G. G., Wagoner, J., Lofgren, E. T., Samore, M. H., Pavia, A. T., Nolen, L. D., Komatsu, K., Oakeson, K., & Keegan, L. T.

    medRxiv

    摘要

    Declining childhood vaccination rates have fueled a resurgence of measles in the United States. Surveillance systems may not accurately measure the true extent of outbreaks. As of May 2026, the largest ongoing measles outbreak in the United States originated along the Utah-Arizona border in a community with high vaccine exemption rates and limited engagement with healthcare systems, leading to incomplete testing and reporting. To quantify the true outbreak size, we used two independent approaches with complementary data sources: a phylodynamic analysis and an agent-based model. Both methods found significant underreporting, estimating the true outbreak size to be 3.1- to 4.8-fold larger than reported, with confirmed cases representing only 20.96%-32.5% total infections. These findings suggest that substantial underreporting of measles occurs, especially in tight knit communities. The use of complementary analytical approaches to evaluate completeness of reporting can reveal the extent of measles transmission and aid control efforts.

  • 2026进行中

    Why Epidemic Risk at the 2026 World Cup May Not Be What You Think

    Lessler, J., Smith, C. P., Das, P., Sykes, A. L., Urbinati, A., Geith, K., Powers, K. A., Davis, J. T., Kern-Allely, S. C., Vega Yon, G. G., Lofgren, E. T., Pearson, C. A. B., & Vespignani, A.

    medRxiv

    摘要

    Background: The 2026 FIFA World Cup may bring over one million visitors to North America from around the globe to participate in mass gathering events. The nature of the event and recent news have raised concerns for some that the tournament could lead to infectious disease outbreaks or fuel existing epidemics. Objective: To systematically assess the infectious disease threat posed to the United States by the tournament. Design: A multi-institutional team evaluated pathogen-specific risk across three dimensions: importation, outbreak potential, and impact to identify a priority pathogen list. A systematic screening protocol ensured common criteria and that pathogen information was collected when necessary to inform inclusion. Results: Increased risk from the World Cup is near zero for 63 of 77 evaluated pathogens. Pathogens were predominantly excluded as threats due to low excess importation risk and low outbreak potential if introduced. The remaining priority pathogens fall into five categories: (a) mosquito borne pathogens with the potential for sustained transmission in some host cities, (b) seasonal respiratory viruses, (c) chronic infections with high prevalence outside the United States, (d) pathogens present in the United States with likely increased transmission at World Cup activities, and (e) high-consequence infectious threats. Limitations: Data availability is variable across diseases. Impact calculations may not reflect actual costs to host cities. Disease incidence in World Cup travelers may differ from national incidence rates. Conclusion: While infectious disease outbreaks at the 2026 FIFA World Cup are possible, in an already highly connected world where large gatherings are frequent, the elevated risk from the tournament is not as extreme as it first may seem. Primary Funding Source: US Centers for Disease Control and Prevention

  • 2026进行中

    Practical Guidelines and Reflections on Building Public Health Software: A Measles Case Study (Preprint)

    Vega Yon, G. G., Thornton, D., Redd, A., Pulsipher, A., Toth, D., Dorsan, E., Rennert, L., Johnson, K., White, L. F., Gruninger, R., Nolen, L. D., & Samore, M. H.

    JMIR Public Health and Surveillance

    摘要

    Academic–public health partnerships are essential for strengthening outbreak preparedness and response, yet translating modeling tools into routine public health practice remains challenging. Structural, technical, and workforce constraints often limit the capacity for modeling tools during emergencies. Here, we describe the development a software ecosystem designed to support real-time infectious disease response through sustained collaboration between an academic research team and public health agencies, with particular focus on the recent measles outbreak. The resulting software enabled real-time scenario modeling, visualization of transmission dynamics, and iterative updates as new data became available. Beyond immediate outbreak response, the initiative strengthened cross-sector collaboration, expanded modeling capacity, and highlighted ongoing gaps in technical infrastructure and workforce readiness at the state and local levels. This case study demonstrates how sustained academic–government partnerships combined with streamlined development practices can accelerate the translation of modeling tools into operational public health settings. Establishing and maintaining analytic infrastructure and agile processes between emergencies may be critical for ensuring timely, data-informed decision-making during future outbreaks.

  • 2026进行中

    Bayesian Generative Modeling for Heterogeneous Wastewater Data Applied to COVID-19 Forecasting

    Johnson, K. E., Vega Yon, G. G., Brand, S. P. C., Bernal Zelaya, C. O., Bayer, D., Volkov, I., Susswein, Z., Magee, A., Gostic, K. M., English, K. M., Ghinai, I., Hamlet, A., Olesen, S. W., Pulliam, J. R. C., Abbott, S., & Morris, D. H.

    medRxiv

    摘要

    Infectious disease forecasts can inform public health decision-making. Wastewater monitoring is a relatively new epidemiological data source with multiple potential applications, including forecasting. Incorporating wastewater data into epidemiological forecasting models is challenging, and relatively few studies have assessed whether this improves forecast performance. We present and evaluate a semi-mechanistic wastewater-informed forecasting model. The model forecasts COVID-19 hospital admissions at the state and territorial levels in the United States, based on incident hospital admissions data and, optionally, SARS-CoV-2 wastewater concentration data from multiple wastewater sampling sites. From February through April 2024, we produced real-time wastewater-informed COVID-19 forecasts using development versions of the model and submitted them to the United States COVID-19 Forecast Hub (“the Hub”). We then published an open-source R package, wwinference , that implements the model with or without wastewater as an input. Using proper scoring rules and measures of model calibration, we assess both our real-time submissions to the Hub and retrospective hypothetical forecasts from wwinference made with and without wastewater data. While the models performed similarly with and without the wastewater signal included, there was substantial heterogeneity for individual locations and dates where wastewater data meaningfully improved or degraded the model’s forecast performance. Compared to other models submitted to the Hub during the period spanned by our submissions, the real-time wastewater-informed version of our model ranked fourth of 10 models, with the hospital admissions-only version of our model ranking second out of 10 models. Across the 2023-2024 winter epidemic wave, retrospective forecasts from wwinference would have performed similarly with and without the wastewater signal included: fifth and fourth out of 10 models, respectively. To better understand the drivers of differential forecast performance with and without wastewater, we performed an exploratory analysis investigating the relationship between characteristics of the input data and improved and reduced performance in our model. Based on that analysis, we identify and discuss key areas for further model development. To our knowledge, this is the first work that conducts an evaluation of real-time and retrospective infectious disease forecasts across the United States both with and without wastewater data and compared to other forecasting models.

  • 2026已发表被引用1

    A Vision for Estimation of the Instantaneous Reproductive Number

    Milando, C. W., Vega Yon, G. G., Johnson, K., Urbinati, A., St-Onge, G., Klein, B., Cori, A., & White, L. F.

    Epidemics

    摘要

    The reproductive number, R t , is a popular metric used for monitoring infectious diseases. R t describes the expected number of infections that will be generated from a single infection at time t , which maps nicely to the likelihood that disease incidence will increase, decrease, or remain constant in the near future. Although this metric has existed for decades, it became more widely used during the COVID-19 pandemic and there was a subsequent proliferation of new estimation methods and software tools. This rapid development of methods and tools presents many opportunities and challenges for users, researchers, and decision makers. In recognition of this growth, we convened a three-day “collabathon” in September 2024 to bring together researchers and public health practitioners to identify challenges and areas for future development in R t estimation and to begin work in these areas. Here we provide a high-level summary of current methods and report on the findings from the collabathon, including a summary of current challenges and recommendations for future development, evaluation and interpretation of R t .

  • 2026已发表

    P-1104. Multidrug-Resistant Organism (MDRO)-Contaminated Mobile Equipment Networks in Skilled Nursing Facilities

    Visnovsky, L. D., Leecaster, M., Vega Yon, G. G., Loc-Carrillo, C. M., Dorsan, E., Huber, T., Jamu, S. M., Stratford, K., Samore, M. H., & Drews, F. A.

    Open Forum Infectious Diseases

    摘要

    Background: Multidrug-resistant organisms (MDROs) are prevalent in skilled nursing facilities (SNFs). Mobile equipment has been linked to outbreaks but its role in MDRO endemicity is less understood. Methods: We conducted 2 waves of 4-day microbiological sampling 3 to 6 months apart in 3 ventilator-capable SNFs (1 academic affiliate, 2 community-based). We collected patient room composite samples at shift start; up to 8 types of shared equipment were sampled at start and end of sampling day and after observed use. Samples were enriched and plated on selective media (for methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus, extended-spectrum β-lactamase producing Enterobacteriaceae, and multidrug-resistant Acinetobacter species). Presumptive MDRO positives were MALDI-confirmed. Wireless sensors in patient rooms and attached to shared equipment recorded equipment location and movement, allowing creation of bipartite networks (nodes: rooms and equipment). Two rooms were connected when the same equipment item visited both rooms. We used Exponential Family Random Graph Models to analyze network structure and test if: 1) a room was more likely to have an MDRO detected if connected by equipment to another room with the same MDRO and 2) MDRO detection frequency differed by facility. Results: 8 types of mobile equipment were studied but only glucometers were shared items at all facilities (Figure 1). Equipment degree (the number of different rooms an item visited during deployment) varied substantially (Figure 1). MDRO contamination depended on facility and equipment type (Figure 2). ESBLs and MRSA were the most common MDROs on room surfaces and mobile equipment. Contamination was low in facility A relative to other facilities (Table 1). Vital signs carts had a high median degree (12) but were rarely contaminated (6%, n=6). Shower beds also had high median degree (9) but were often contaminated (25%, n=13) in the two facilities that used them. Network analysis of facility B found that rooms connected by shared equipment were more likely to be contaminated by the same MDRO than unconnected rooms (p< 0.05). Conclusion: Shared equipment in SNFs moves between patient rooms and is often MDRO-contaminated. Future work should study the role of shared equipment in MDRO transmission.

  • 2025已发表被引用1

    The impact of social norms on diffusion dynamics: A simulation of e-cigarette use behavior

    Piombo, S., Vega Yon, G. G., & Valente, T. W.

    Health Education & Behavior

    摘要

    Diffusion of innovations theory can be used to understand how to prevent or slow the spread of harmful behaviors, such as e-cigarette use in adolescent social networks. This study explores how different network intervention strategies could impact diffusion dynamics through network simulations based on observed social norms and e-cigarette use data. Simulations were initialized with baseline network data collected from 10 schools in a prospective cohort study of adolescent social networks and health behaviors in Southern California. Diffusion conditions varied by changes in social norms for intervention nodes (pro-e-cigarette, anti-e-cigarette, or neutral norms) and intervention strategy, where greater pro- and anti-tobacco norms were assigned to 15% of the network based on four intervention seeding conditions: opinion leadership, betweenness centrality, segmentation, and random selection. For each network, simulations were run using the netdiffuseR package in R and multivariate generalized linear models were estimated to examine changes in diffusion dynamics. Diffusion prevalence and rate were greater in denser networks and networks with more initial e-cigarette users. Anti-e-cigarette norms significantly decreased average prevalence across all intervention conditions. Strategically selecting high betweenness centrality nodes and opinion leader nodes significantly decreased the average prevalence of e-cigarette use. The results of this study show that achieving a change in norms for 15% of a network can substantially impact e-cigarette use prevalence. Furthermore, this study enhances our knowledge of how personal and network factors affect diffusion dynamics and demonstrates that targeting social norms through network-based interventions is one avenue for slowing the spread of harmful behaviors.

  • 无日期已发表

    A Novel Approach for Classifying Monoamine Neurotransmitters by Applying Machine Learning on UV Plasmonic-Engineered Auto Fluorescence Time Decay Series (AFTDS)

    Mohammadi, M., Najafzadehkhoei, S., Vega Yon, G. G., & Wang, Y.

    Nanoscale Advances

    摘要

    This study introduces a hybrid approach integrating advanced plasmonic nanomaterials and machine learning (ML) for high-precision biomolecule detection. We leverage aluminum concave nanocubes (AlCNCs) as an innovative plasmonic substrate to enhance the native fluorescence of neurotransmitters, including dopamine (DA), norepinephrine (NE), and 3,4-dihydroxyphenylacetic acid (DOPAC). AlCNCs amplify weak fluorescence signals, enabling probe-free, label-free detection and differentiation of these molecules with great sensitivity and specificity. To further improve classification accuracy, we employ ML algorithms, with Long Short-Term Memory (LSTM) networks playing a central role in analyzing time-dependent fluorescence data. Comparative evaluations with k-nearest neighbors (KNN) and Random Forest (RF) demonstrate the superior performance of LSTM in distinguishing neurotransmitters. The results reveal that AlCNC substrates provide up to a 12-fold enhancement in fluorescence intensity for DA, 9-fold for NE, and 7-fold for DOPAC compared to silicon substrates. At the same time, ML algorithms achieve classification accuracy exceeding 89%. This interdisciplinary methodology bridges the gap between nanotechnology and ML, showcasing the synergistic potential of AlCNC-enhanced native fluorescence and ML in biosensing. The framework paves the way for probe-free, label-free biomolecule profiling, offering transformative implications for biomedical diagnostics and neuroscience research.

  • 2024已发表被引用3

    Imaginary Network Motifs: Structural Patterns of False Positives and Negatives in Social Networks

    Tanaka, K., & Vega Yon, G. G.

    Social Networks

    Cognitive errorsCognitive Social StructuresNetwork motifsNetwork perceptionsSocial networks

    摘要

    We examine the structural patterns in the cognitive representation of social networks by systematically classifying false positives and negatives. Although existing literature on Cognitive Social Structures (CSS) has begun exploring false positives and negatives by comparing actual and perceived networks, it has not differentiated simultaneous occurrences of true and false positives and negatives on network motifs, such as reciprocity and triadic closure. Here, we propose a theoretical framework to categorize three classes of errors we call imaginary network motifs as combinations of accurately and erroneously perceived ties: (a) partially false, (b) completely false, and (c) mixed false. Using four published CSS data sets, we empirically test which imaginary network motifs are significantly more or less present in different types of perceived networks than the corresponding actual networks. Our results confirm that people not only fill in the blanks as suggested in the prior research but also conceive other imaginary structures. The findings advance our understanding of perception gaps between actual and perceived networks and have implications for designing more accurate network modeling and sampling.

  • 2024已发表被引用4

    Assessing the Dynamics of PrEP Adoption in a National-Scale Physician Network

    Sargent, M., Matthews, L. J., Vega Yon, G. G., Storholm, E. D., Ober, A. J., & Green, H. D.

    Social Networks

    摘要

    This study examines the adoption of a new preventive treatment for HIV called preexposure prophylaxis (PrEP) in a nation-wide network of US physicians. We compare the structure of these networks across nine multi-state census regions, and assess geographic variations in network structure. Within these networks, we measured the adoption threshold associated with physician adoption of PrEP. The low threshold values that we observe are consistent with the hypothesis that slow PrEP adoption is the result of a lack of knowledge and exposure among physicians. Regression results demonstrate the mix of market, epidemiological, and socio/cultural factors that shape adoption thresholds.

  • 2024已发表

    Incorporating Social Determinants of Health into Transmission Modeling of COVID-19 Vaccine in the US: A Scoping Review

    Duong, K. N. C., Nguyen, D. T., Kategeaw, W., Liang, X., Khaing, W., Visnovsky, L. D., Veettil, S. K., McFarland, M. M., Nelson, R. E., Jones, B. E., Pavia, A. T., Coates, E., Khader, K., Love, J., Vega Yon, G. G., Zhang, Y., Willson, T., Dorsan, E., Toth, D. J. A., Jones, M. M., Samore, M. H., & Chaiyakunapruk, N.

    The Lancet Regional Health - Americas

    摘要

    During COVID-19 in the US, social determinants of health (SDH) have driven health disparities. However, the use of SDH in COVID-19 vaccine modeling is unclear. This review aimed to summarize the current landscape of incorporating SDH into COVID-19 vaccine transmission modeling in the US. Medline and Embase were searched up to October 2022. We included studies that used transmission modeling to assess the effects of COVID-19 vaccine strategies in the US. Studies' characteristics, factors incorporated into models, and approaches to incorporate these factors were extracted. Ninety-two studies were included. Of these, 11 studies incorporated SDH factors (alone or combined with demographic factors). Various sets of SDH factors were integrated, with occupation being the most common (8 studies), followed by geographical location (5 studies). The results show that few studies incorporate SDHs into their models, highlighting the need for research on SDH impact and approaches to incorporating SDH into modeling. Funding: This research was funded by the Centers for Disease Control and Prevention (CDC).

  • 2023已发表被引用5

    Power and Multicollinearity in Small Networks: A Discussion of “Tale of Two Datasets: Representativeness and Generalisability of Inference for Samples of Networks” by Krivitsky, Coletti, and Hens

    Vega Yon, G. G.

    Journal of the American Statistical Association

    摘要

    The recent work by Krivitsky, Coletti & Hens [KCH] provides an important new contribution to the Exponential-Family Random Graph Models [ERGMs], a start-to-finish approach to dealing with multi-network ERGMs. Although multi-network ERGMs have been around for a while (mostly in the form of block-diagonal models and multi-level ERGMs, see Duxbury and Wertsching (2023), Wang et al. (2013), Slaughter and Koehly (2016)), not much care has been given to the estimation and post-estimation steps. In their paper, Krivitsky, Coletti & Hens give a detailed layout of how to build, estimate, and analyze multi-ERGMs with heterogeneous data sources. In this comment, I will focus on two issues the authors did not discuss, namely, sample size requirements and multicollinearity.

  • 2023已发表被引用2

    epiworldR: Fast Agent-Based Epi Models

    Meyer, D., & Vega Yon, G. G.

    Journal of Open Source Software

    摘要

    Agent-based modeling (ABM) has emerged as a powerful computational approach to studying complex systems across various fields, including social sciences and epidemiology. By simulating the interactions and behaviors of individual entities, known as agents, ABM provides a unique lens through which researchers can analyze and understand the emergent properties and dynamics of these systems. The epiworldR package provides a flexible framework for ABM implementation and methods for prototyping disease outbreaks and transmission models using a C++ backend. It supports multiple epidemiological models, including the Susceptible-Infected-Susceptible (SIS), Susceptible-Infected-Removed (SIR), Susceptible-Exposed-Infected-Removed (SEIR), and others, involving arbitrary mitigation policies and multiple-disease models. Users can specify transmission/susceptibility rates as a function of agents' features, providing great complexity for the model dynamics.

  • 2023已发表被引用1

    Veteran Perspectives of Epilepsy Care: Impact of Veteran Satisfaction, Knowledge, and Proactivity

    Panahi, S., Kennedy, E., Roghani, A., Vega Yon, G. G., VanCott, A., Gugger, J. J., Raquel Lopez, M., & Pugh, M. J.

    Epilepsy & Behavior

    摘要

    Objective: Veterans are at elevated risk of epilepsy due to higher rates of traumatic brain injury (TBI). However, little work has examined the extent to which quality of care is associated with key outcomes for Veterans with epilepsy (VWE). This study aimed to examine the impact of quality of care on three outcomes: patients' knowledge of epilepsy self-care, proactive epilepsy self-management, and satisfaction with care. Method: We conducted a cross-sectional study of Post-9/11 Veterans with validated active epilepsy who received VA care (n = 441). Veterans were surveyed on care processes using American Academy of Neurology epilepsy quality measures, and a patient-generated measure related to the use of emergency care. Outcome measures included epilepsy self-care knowledge, proactive epilepsy self-management, and satisfaction with epilepsy care. Covariates included sociodemographic and health status variables and a measure of patient-provider communication. An ordinary least-squares (OLS) regression model was used to determine if the quality of care was associated with the outcomes adjusting for multiple comparisons. Results: Self-reported measures of quality of care were broadly associated with satisfaction with care and epilepsy knowledge. OLS modeling indicated that healthcare provider guidance on when to seek emergency care was significantly associated with higher Veteran satisfaction with care (p $<$ 0.01). Veterans who were asked about seizure frequency at every visit by their provider also reported higher satisfaction with care (p $<$ 0.01) and increased epilepsy knowledge (p $<$ 0.01). Veteran-provider communication was positively associated with epilepsy knowledge and proactive epilepsy self-management. Veterans with epilepsy with drug resistance epilepsy were significantly less satisfied with their care and reported lower proactivity compared to epilepsy controlled with medications. Further analysis indicated Black VWEs reported lower scores on epilepsy self-care knowledge compared to Whites (p $<$ 0.001). Conclusions: This study found that quality measures were associated with satisfaction and epilepsy knowledge but not associated with proactive self-management in multivariable models. The finding that better communication between providers and Veterans suggests that in addition to technical quality, interpersonal quality is important for patient outcomes. The secondary analysis identified racial disparities in epilepsy knowledge. This work offers opportunities to improve the quality of epilepsy care through the practice of patient-centered care models that reflect Veteran priorities and perceptions.

  • 2023进行中被引用2

    Characterizing Spatiotemporal Variation in Transmission Heterogeneity during the 2022 Mpox Outbreak in the USA

    Love, J., LaPrete, C. R., Sheets, T. R., Vega Yon, G. G., Thomas, A., Samore, M. H., Keegan, L. T., Adler, F. R., Slayton, R. B., Spicknall, I. H., & Toth, D. J. A.

    Epidemiology

    摘要

    Understanding how transmission heterogeneity varies over the course of an enduring infectious disease outbreak improves understanding of observed disease dynamics and informs public health strategy. We quantified the spatiotemporal variation in transmission heterogeneity for the 2022 mpox outbreak in the US using the dispersion parameter of the offspring distribution, k . Our methods fit negative binomial distributions to transmission chain offspring distributions informed by a large mpox contact tracing dataset. We found that estimates of transmission heterogeneity varied across the outbreak, but overall estimated transmission heterogeneity was low. When testing our methods on simulated data, estimate accuracy depended on contact tracing data accuracy and completeness. Because the actual contact tracing data had high incompleteness, the values of k estimated from the empirical data may therefore be artificially high. Through simulation, we explore a method to correct estimated k for data incompleteness and, further, explore baseline expectations for temporal dynamics of k .

  • 2022进行中

    Discrete Exponential-Family Models for Multivariate Binary Outcomes

    Vega Yon, G. G., Pugh, M. J., & Valente, T. W.

    arXiv

    摘要

    Studies that collect multi-outcome data such as tobacco and alcohol use are becoming increasingly common. In principle, multi-outcomes studies investigate the correlations between outcomes, including, causal links and/or joint distributions. Although there are many methods for studying multivariate outcomes, significant limitations regarding scale and interpretation persist. Here we introduce a model based on the exponential-family for discrete binary outcomes that provides a flexible framework for hypothesis testing of multiple binary outcomes in a computationally efficient fashion.

  • 2022已发表被引用20

    Officer Networks and Firearm Behaviors: Assessing the Social Transmission of Weapon-Use

    Ouellet, M., Hashimi, S., & Vega Yon, G. G.

    Journal of Quantitative Criminology

    摘要

    Objectives: We reconstruct the networks of officers co-involved in force incidents to test whether interactions with weapon-prone peers impact firearm use. Methods: We draw from a statewide dataset of force incidents across law enforcement agencies in New Jersey, and employ conditional likelihood models to estimate whether exposure to peers with histories of firearm use is associated with an officer's own likelihood of firearm use net of other contextual confounders. Results: We find preliminary evidence that officer firearm behaviors, including drawing, pointing, and discharging a firearm, is influenced by an officer's peers. Greater exposure to colleagues with histories of firearm use is associated with a lower risk of using a firearm. We also find that officer features, including experience and race/ethnicity, are associated with the risk of firearm use. Conclusions: Our study suggests officers' peers structure the risk of firearm use. Our data allow us to look at time order and rule out situational confounders pertaining to firearm use; however, do not allow us to infer causality. We discuss the study's implications for understanding firearm behaviors and the role of network science in moving policing research forward.

  • 2022已发表被引用4

    The formation of political discussion networks

    Hâncean, M., Perc, M., Vega Yon, G. G., Gheorghiță, A., & Mihăilă, B.

    Royal Society Open Science

    摘要

    Dialogues among politicians provide a window into political landscapes and relations among parties and nations. Existing research has focused on the outcomes of such dialogues and on the structure of social networks on which they take place. Little is known, however, about how political discussion networks form and which are the main driving forces behind their formation. We study a collection of ego-networks from 30 randomly sampled Romanian politicians to reveal fundamental processes behind the formation of political discussion networks. We show that ties in such networks tend to be strong and balanced, and that their organization is not affected by sex, age or education homophily. We use the exponential family of random graph models for small networks to assess likely closure mechanisms and possible homophily effects, but we note that further research and additional data are needed to fully understand the impact of context and political affiliations on the generalization of our findings.

  • 2021已发表被引用5

    Building, Importing, and Exporting GEXF Graph Files with rgexf

    Vega Yon, G. G.

    Journal of Open Source Software

    摘要

    First introduced in 2012, the rgexf package for the R programming language was the first effort to make the Graph Exchange XML Format (GEXF) specification available to the R world. With more than 500,000 downloads, it is one of the most popular ways to incorporate GEXF files into the R programming language environment. Beyond reading and writing GEXF files from within R, the rgexf R package has various other features that can help to create beautiful network visualizations: users can create GEXF objects from scratch, adding and removing nodes and edges as needed; users of the igraph package can directly convert objects between gexf and igraph classes; and, thanks to the gexf-js javascript library, users can immediately visualize their network objects in the web browser.

  • 2021已发表被引用1

    Bayesian parameter estimation for automatic annotation of gene functions using observational data and phylogenetic trees

    Vega Yon, G. G., Thomas, D. C., Morrison, J., Mi, H., Thomas, P. D., & Marjoram, P.

    PLOS Computational Biology

    摘要

    Gene function annotation is important for a variety of downstream analyses of genetic data. But experimental characterization of function remains costly and slow, making computational prediction an important endeavor. Phylogenetic approaches to prediction have been developed, but implementation of a practical Bayesian framework for parameter estimation remains an outstanding challenge. We have developed a computationally efficient model of evolution of gene annotations using phylogenies based on a Bayesian framework using Markov Chain Monte Carlo for parameter estimation. Unlike previous approaches, our method is able to estimate parameters over many different phylogenetic trees and functions. The resulting parameters agree with biological intuition, such as the increased probability of function change following gene duplication. The method performs well on leave-one-out cross-validation, and we further validated some of the predictions in the experimental scientific literature.

  • 2021已发表被引用47

    Exponential random graph models for little networks

    Vega Yon, G. G., Slaughter, A., & de la Haye, K.

    Social Networks

    摘要

    Statistical models for social networks have enabled researchers to study complex social phenomena that give rise to observed patterns of relationships among social actors and to gain a rich understanding of the interdependent nature of social ties and actors. Much of this research has focused on social networks within medium to large social groups. To date, these advances in statistical models for social networks, and in particular, of Exponential-Family Random Graph Models (ERGMS), have rarely been applied to the study of small networks, despite small network data in teams, families, and personal networks being common in many fields. In this paper, we revisit the estimation of ERGMs for small networks and propose using exhaustive enumeration when possible. We developed an R package that implements the estimation of pooled ERGMs for small networks using Maximum Likelihood Estimation (MLE), called ergmito. Based on the results of an extensive simulation study to assess the properties of the MLE estimator, we conclude that there are several benefits of direct MLE estimation compared to approximate methods and that this creates opportunities for valuable methodological innovations that can be applied to modeling social networks with ERGMs.

  • 2020已发表被引用70

    Diffusion/Contagion Processes on Social Networks

    Valente, T. W., & Vega Yon, G. G.

    Health Education & Behavior

    摘要

    This study models how new ideas, practices, or diseases spread within and between communities, the diffusion of innovations or contagion. Several factors affect diffusion such as the characteristics of the initial adopters, the seeds; the structure of the network over which diffusion occurs; and the shape of the threshold distribution, which is the proportion of prior adopting peers needed for the focal individual to adopt. In this study, seven seeding conditions are modeled: (1) three opinion leadership indicators, (2) two bridging measures, (3) marginally positioned seeds, and (4) randomly selected seeds for comparison. Three network structures are modeled: (1) random, (2) small-world, and (3) scale-free. Four threshold distributions are modeled: (1) normal; (2) uniform; (3) beta 7,14; and (4) beta 1,2; all of which have a mean threshold of 33%, with different variances. The results show that seeding with nodes high on in-degree centrality and/or inverse constraint has faster and more widespread diffusion. Random networks had faster and higher prevalence of diffusion than scale-free ones, but not different from small-world ones. Compared with the normal threshold distribution, the uniform one had faster diffusion and the beta 7,14 distribution had slower diffusion. Most significantly, the threshold distribution standard deviation was associated with rate and prevalence such that higher threshold standard deviations accelerated diffusion and increased prevalence. These results underscore factors that health educators and public health advocates should consider when developing interventions or trying to understand the potential for behavior change.

  • 2019已发表被引用18

    parallel: A command for parallel computing

    Vega Yon, G. G., & Quistorff, B.

    The Stata Journal: Promoting communications on statistics and Stata

    摘要

    The parallel package allows parallel processing of tasks that are not interdependent. This allows all flavors of Stata to take advantage of multiprocessor machines. Even Stata/MP users can benefit because many community-contributed programs are not automatically parallelized but could be under our framework.

  • 2019已发表被引用8

    fmcmc: A friendly MCMC framework

    Vega Yon, G. G., & Marjoram, P.

    Journal of Open Source Software

    摘要

    Markov Chain Monte Carlo (MCMC) is used in a variety of statistical and computational venues such as: statistical inference, Markov quadrature (also known as Monte Carlo integration), stochastic optimization, among others. The fmcmc R package provides a flexible framework for implementing MCMC methods that use the Metropolis-Hastings algorithm. fmcmc provides the following out-of-the-box features that can be valuable for both practitioners of MCMC and educators: seamless efficient multiple-chain sampling using parallel computing, user-defined transition kernels, and automatic stop using convergence monitoring.

  • 2019已发表被引用3

    slurmR: A lightweight wrapper for HPC with Slurm

    Vega Yon, G. G., & Marjoram, P.

    Journal of Open Source Software

    摘要

    Nowadays, high-performance-computing (HPC) clusters are commonly available tools for either in or out of cloud settings. The Slurm Workload Manager is a program written in C that is used to efficiently manage resources in HPC clusters. While the R programming language has not been developed for HPC settings, there are currently several ways in which R can be enhanced by means of HPC. The slurmR R package is one of those ways: it provides tools for using R in HPC settings that work with Slurm, offering wrappers and auxiliary functions that allow the user to seamlessly integrate their analysis pipeline with HPC, putting emphasis on providing the user with a family of functions similar to those that the parallel R package provides. In summary, slurmR provides a dependency-free and purpose-built alternative for R users working in a HPC environment with Slurm.

  • 2019已发表被引用11

    Sensing eating mimicry among family members

    Bell, B. M., Spruijt-Metz, D., Vega Yon, G. G., Mondol, A. S., Alam, R., Ma, M., Emi, I., Lach, J., Stankovic, J. A., & de la Haye, K.

    Translational Behavioral Medicine

    EatingFamilyMimicryObesityPermutation testsSocial influence

    摘要

    Family relationships influence eating behavior and health outcomes (e.g., obesity). Because eating is often habitual (i.e., automatically driven by external cues), unconscious behavioral mimicry may be a key interpersonal influence mechanism for eating within families. This pilot study extends existing literature on eating mimicry by examining whether multiple family members mimicked each other's bites during natural meals. Thirty-three participants from 10 families were videotaped while eating an unstructured family meal in a kitchen lab setting. Videotapes were coded for participants' bite occurrences and times. We tested whether the likelihood of a participant taking a bite increased when s/he was externally cued by a family eating partner who had recently taken a bite (i.e., bite mimicry). A paired-sample t-test indicated that participants had a significantly faster eating rate within the 5 s following a bite by their eating partner, compared to their bite rate at other times (t = 7.32, p $<$ .0001). Nonparametric permutation testing identified five of 78 dyads in which there was significant evidence of eating mimicry; and 19 of 78 dyads that had p values $<$ .1. This pilot study provides preliminary evidence that suggests eating mimicry may occur among a subset of family members, and that there may be types of family ties more prone to this type of interpersonal influence during meals.

  • 2019已发表被引用14

    Network influences on policy implementation: Evidence from a global health treaty

    Valente, T. W., Wipfli, H., & Vega Yon, G. G.

    Social Science and Medicine

    Diffusion of innovationsPolicy implementationSocial network analysisTobacco control

    摘要

    This paper examines whether country implementation of a public health treaty is influenced by the implementation behaviors of other countries to which they have network ties. We examine implementation of the Framework Convention on Tobacco Control (FCTC) adopted by the World Health Organization in 2003 and ratified by approximately 94% of countries as of 2016. We constructed five networks: (1) geographic distance, (2) general trade, (3) tobacco trade, (4) GLOBALink referrals, and (5) GLOBALink co-subscriptions. Network exposure terms were constructed from these networks based on the implementation scores for six articles of the FCTC treaty. We estimate effects using a lagged Type 1 Tobit model. Results show that network effects were significant: (a) across all networks for article 6 (pricing and taxation), (b) distance, general trade, GL referrals, and GL co-subscriptions for article 8 (second hand smoke), (c) distance, general trade, and GL co-subscriptions for article 11 (packaging and labeling), and (d) distance and GL co-subscription for article 13 (promotion and advertising), (e) tobacco trade and GL co-subscriptions for article 14 (cessation). These results indicate that diffusion effects were more prevalent for pricing and taxation as well as restrictions on smoking in public places and packaging and labeling. These results suggest that network influences are possible in domains that are amenable to control by national governments but unlikely to occur in domains established by existing regulatory systems. Implications for future studies of policy implementation are discussed.

  • 2019已发表被引用16

    Smoking Diffusion through Networks of Diverse, Urban American Adolescents over the High School Period

    de la Haye, K., Shin, H., Vega Yon, G. G., & Valente, T. W.

    Journal of Health and Social Behavior

    adolescentdiffusionhigh schoolsmoking initiationsocial networkstochastic actor-based model

    摘要

    This study uses recent data to investigate if smoking initiation diffuses through friendship networks over the high school period and explores if diffusion processes differ across schools. One thousand four hundred and twenty-five racially and ethnically diverse youth from four high schools in Los Angeles were surveyed four times over the high school period from 2010 to 2013. Probit regression models and stochastic actor-based models for network dynamics tested for peer effects on smoking initiation. Friend smoking was found to predict adolescent smoking, and smoking initiation diffused through friendship networks in some but not all of the schools. School differences in smoking rates and the popularity of smokers may be linked to differences in the diffusion of smoking through peer networks. We conclude that there are differences in peer effects on smoking initiation across schools that will be important to account for in network-based smoking interventions.

  • 2013已发表被引用3

    El impacto del rating televisivo sobre la actividad en Twitter: evidencia para Chile sobre la base del evento TELETÓN 2012

    Fábrega Lacoa, J., & Vega Yon, G. G.

    Cuadernos.info

    摘要

    ¿Tiene un impacto el rating televisivo sobre el volumen de actividad en Twitter? El surgimiento de medios sociales vía Internet está modificando las prácticas en la industria televisiva. En particular, los canales de televisión están integrando en sus programaciones de forma explícita la interacción con las audiencias vía medios sociales. Estos esfuerzos se están realizando motivados más por la intuición que por evidencia respecto a la eficacia de los mismos. Para contribuir a identificar el real impacto de los contenidos televisivos sobre la actividad en el medio social Twitter, este estudio propone el análisis estadístico de la relación entre rating televisivo y actividad en Twitter durante la transmisión de un mismo evento por todos los canales de televisión, la Teletón 2012. Los resultados sugieren la existencia de un impacto positivo y estadísticamente significativo que vincula el rating televisivo con la actividad en Twitter. Específicamente, durante el evento Teletón 2012, un aumento de un 1 punto del rating televisivo significó incrementos promedios de 1.5 tweets por minuto para el conjunto de la transmisión y de 6 tweets por minuto en horario prime.


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