Search

Forecasting infection case counts and estimating accurate epidemiological parameters are critical components of managing the response to a pandemic. This paper describes a modular, extensible framework for a COVID-19 forecasting system, primarily deployed during the first Covid wave in Mumbai and Jharkhand, India. We employ a variant of the SEIR compartmental model motivated by the nature of the available data and operational constraints. We estimate best fit parameters using Sequential Model-Based Optimization (SMBO), and describe the use of a novel, fast and approximate Bayesian model averaging method (ABMA) for parameter uncertainty estimation that compares well with a more rigorous Markov Chain Monte Carlo (MCMC) approach in practice. We address on-the-ground deployment challenges such as spikes in the reported input data using a novel weighted smoothing method. We describe extensive empirical analyses to evaluate the accuracy of our method on ground truth as well as against other state-of-the-art approaches. Finally, we outline deployment lessons and describe how inferred model parameters were used by government partners to interpret the state of the epidemic and how model forecasts were used to estimate staffing and planning needs essential for addressing COVID-19 hospital burden.CCS CONCEPTSApplied computing → Health care information systems; Forecasting;Computing methodologies → Modeling methodologies.

Short-term probabilistic forecasts of the trajectory of the COVID-19 pandemic in the United States have served as a visible and important communication channel between the scientific modeling community and both the general public and decision-makers. Forecasting models provide specific, quantitative, and evaluable predictions that inform short-term decisions such as healthcare staffing needs, school closures, and allocation of medical supplies. Starting in April 2020, the US COVID-19 Forecast Hub (https://covid19forecasthub.org/) collected, disseminated, and synthesized tens of millions of specific predictions from more than 90 different academic, industry, and independent research groups. A multi-model ensemble forecast that combined predictions from dozens of different research groups every week provided the most consistently accurate probabilistic forecasts of incident deaths due to COVID-19 at the state and national level from April 2020 through October 2021. The performance of 27 individual models that submitted complete forecasts of COVID-19 deaths consistently throughout this year showed high variability in forecast skill across time, geospatial units, and forecast horizons. Two-thirds of the models evaluated showed better accuracy than a naïve baseline model. Forecast accuracy degraded as models made predictions further into the future, with probabilistic error at a 20-week horizon 3-5 times larger than when predicting at a 1-week horizon. This project underscores the role that collaboration and active coordination between governmental public health agencies, academic modeling teams, and industry partners can play in developing modern modeling capabilities to support local, state, and federal response to outbreaks. Significance Statement This paper compares the probabilistic accuracy of short-term forecasts of reported deaths due to COVID-19 during the first year and a half of the pandemic in the US. Results show high variation in accuracy between and within stand-alone models, and more consistent accuracy from an ensemble model that combined forecasts from all eligible models. This demonstrates that an ensemble model provided a reliable and comparatively accurate means of forecasting deaths during the COVID-19 pandemic that exceeded the performance of all of the models that contributed to it. This work strengthens the evidence base for synthesizing multiple models to support public health action.

Accurate forecasts of infections for localized regions are valuable for policy making and medical capacity planning. Existing compartmental and agent-based models [1, 7–11] for epidemiological forecasting employ static parameter choices and cannot be readily contextualized, while adaptive solutions [4, 13] focus primarily on the reproduction number. In the current work, we propose a novel model-agnostic Bayesian optimization approach [3] for learning model parameters from observed data that generalizes to multiple application-specific fidelity criteria. Empirical results demonstrate the efficacy of the proposed approach with SEIR-like compartmental models on COVID-19 case forecasting tasks. A city-level forecasting system based on this approach is being used for COVID-19 response in a few highly impacted Indian cities.

Social networks such as Facebook and Twitter offer a huge opportunity to tap the collective wisdom (both published and yet to be published) of all the participating users in order to address the information needs of individual users in a highly contextualized fashion using rich user-specific information. Realizing this opportunity, however, requires addressing two key limitations of current social networks: (a) difficulty in discovering relevant content beyond the immediate neighborhood, (b) lack of support for information filtering based on semantics, content source and linkage. We propose a scalable framework for constructing smart news feeds based on predicting user-post relevance using multiple signals such as text content and attributes of users and posts, and various user-user, post-post and user-post relations (e.g. friend, comment, author relations). Our solution comprises of two steps where the first step ensures scalability by selecting a small set of user-post dyads with potentially interesting interactions using inverted feature indexes. The second step models the interactions associated with the selected dyads via a joint latent factor model, which assumes that the user/post content and relationships can be effectively captured by a common latent representation of the users and posts. Experiments on a Facebook dataset using the proposed model lead to improved precision/recall on relevant posts indicating potential for constructing superior quality news feeds.

We make the case for developing a web of concepts by starting with the current view of web (comprised of hyperlinked pages, or documents, each seen as a bag of words), extracting concept-centric metadata, and stitching it together to create a semantically rich aggregate view of all the information available on the web for each concept instance. The goal of building and maintaining such a web of concepts presents many challenges, but also offers the promise of enabling many powerful applications, including novel search and information discovery paradigms. We present the goal, motivate it with example usage scenarios and some analysis of Yahoo! logs, and discuss the challenges in building and leveraging such a web of concepts. We place this ambitious research agenda in the context of the state of the art in the literature, and describe various ongoing efforts at Yahoo! Research that are related.

We propose a novel statistical method to predict large scale dyadic response variables in the presence of covariate information. Our approach simultaneously incorporates the effect of covariates and estimates local structure that is induced by interactions among the dyads through a discrete latent factor model. The discovered latent factors provide a redictive model that is both accurate and interpretable. We illustrate our method by working in a framework of generalized linear models, which include commonly used regression techniques like linear regression, logistic regression and Poisson regression as special cases. We also provide scalable generalized EM-based algorithms for model fitting using both "hard" and "soft" cluster assignments. We demonstrate the generality and efficacy of our approach through large scale simulation studies and analysis of datasets obtained from certain real-world movie recommendation and internet advertising applications.

Motivated by the problem of customer wallet estimation, we propose a new setting for multi-view regression, where we learn a completely unobserved target (in our case, customer wallet) by modeling it as a "central link" in a directed graphical model, connecting multiple sets of observed variables. The resulting conditional independence allows us to reduce the maximum discriminative likelihood estimation problem to a convex optimization problem for exponential linear models. We show that under certain modeling assumptions, in particular, when there exist two conditionally independent views and the noise is Gaussian, this problem can be reduced to a single least squares regression. Thus, for this specific, but widely applicable setting, the "unsupervised" multi-view problem can be solved via a simple supervised learning approach. This reduction also allows us to test the statistical independence assumptions underlying the graphical model and perform variable selection. We demonstrate the effectiveness of our approach on our motivating problem of customer wallet estimation and on simulation data.

We present ongoing research that applies statistical relational learning techniques, in particular, propositionalization, to the challenging and interesting real-world domain of functional gene classification of the Yeast genome Sachharomyces Cerevisiae. The main objective of this paper is to identify and describe the structural and statistical properties of this domain and examine how they conflict with the assumptions of relational learning approaches. Such properties are, in fact, shared by many relational application domains and potential solutions will be of interest far beyond the particular genetic application. We show in the last part some preliminary experimental results on potential approaches to overcome such limitations by extending the existing automated feature construction strategies to accommodate the specific domain properties.