Joint QF-STAT PhD Webinars
Organizers: Prof. Stan Uryasev (Email), Prof. Wei Zhu (Email), Mr. Liting Chiang (Email)
Zoom Link and Password: Request by e-mailing to Mrs. Laurie Dalessio (email@example.com)
Spring 2023 Semester
Jack Peters and Taras Vorobets | 10 February 2023 | Pricing European Cryptocurrency Options using Numerical Replication.
Speaker: Jack Peters and Taras Vorobets
Title: Pricing European Cryptocurrency Options using Numerical Replication.
Date/Time: 10 Feb. 2023, Friday, 10:00 AM - 11:00 AM
Abstract: In this case study, using the methodical approach of Ryabchenko, Sarykalin, and Uryasev, we price European style options for Bitcoin and Ethereum. This approach involves approximating the value of an option by using a portfolio consisting of the underlying and a risk-free bond. Using quadratic programming, we produce tables of call and put prices based on the price of the underlying. We model the price of an asset using a set of sample-paths generated from historical prices which we massage to reflect the current volatility of the market.
Anton Malandii | 24 February 2023| SVR Quadrangle
Speaker: Anton Malandii
Title: SVR Quadrangle
Date/Time: 24 Feb. 2023, Friday, 10:00 AM - 11:00 AM
Abstract: Support Vector Regression (SVR) is investigated in the context of the fundamental risk quadrangle paradigm. It is shown that both formulations of SVR, $\varepsilon$-SVR and $\nu$-SVR, correspond to the minimization of equivalent regular error measures (Vapnik error and superquantile (CVaR) norm, respectively) with a regularization penalty. These error measures, in turn, give rise to corresponding risk quadrangles. Additionally, the technique used for the construction of quadrangles serves as a powerful tool in proving the equivalence between $\varepsilon$-SVR and $\nu$-SVR. In general, the Support Vector (SV) algorithm, which is firmly grounded in the framework of Vapnik-Chervonenkis (VC) theory, is proven to be a highly effective classification tool and a generalization of regression. In the context of VC theory, a problem of function estimation relies on the so-called principle of empirical risk minimization, which is essentially a minimization of the expected value of the loss function of the regression residual. The fundamental risk quadrangle theory takes another approach. The concept of generalized regression in this paradigm is developed through the regular measure of error, which is defined axiomatically and, therefore, takes it beyond the expected loss types of error. However, it turns out that errors of expectation type play a significant role in statistical estimation. In particular, regression with respect to a regular error measure of expectation type estimates the corresponding conditional statistic from the same quadrangle (e.g., least-squares regression estimates conditional mean, quantile regression estimates conditional quantile). By constructing the fundamental risk quadrangle, which corresponds to SVR, we show that SVR is the asymptotically unbiased estimator of the average of two symmetric conditional quantiles. Additionally, SVR is formulated as a regular deviation minimization problem with a regularization penalty by invoking Error Shaping Decomposition of Regression. Finally, the dual formulation of SVR in the risk quadrangle framework is derived.
Li Chen | 10 March 2023 | Confidence Estimation Using Unlabeled Data
Speaker: Li Chen
Title: Confidence Estimation Using Unlabeled Data
Date/Time: 10 Mar. 2023, Friday, 10:00 AM - 11:00 AM
Abstract: Overconfidence is a common issue for deep neural networks, limiting their deployment in real-world applications. To better estimate confidence, existing methods mostly focus on fully-supervised scenarios and rely on training labels. We propose the first confidence estimation method for a semi-supervised setting, when most training labels are unavailable. We stipulate that even with limited training labels, we can still reasonably approximate the confidence of model on unlabeled samples by inspecting the prediction consistency through the training process. We use training consistency as a surrogate function and propose a consistency ranking loss for confidence estimation. On both image classification and segmentation tasks, our method achieves state-of-the-art performances in confidence estimation. Furthermore, we show the benefit of the proposed method through a downstream active learning task.
Vince Zhu | 31 March 2023 | Referring Video Object Segmentation with Multi-Level Cross Refined Queries
Speaker: Vince Zhu
Title: Referring Video Object Segmentation with Multi-Level Cross Refined Queries
Date/Time: 31 Mar. 2023, Friday, 10:00 AM - 11:00 AM
Abstract: Referring video object segmentation generates a sequence of segmentation masks for objects referred by text queries, given an input video and a language query. State-of-the-art (SOTA) methods adopt a fixed number of learnable queries to represent instances in each frame independently. Overall accuracy could be impacted by low quality object queries due to frames with significant occlusions or appearance changes in the video. To address the limitation, we propose Cross Filtering and Refinement Transformer (XFRT), which co-filters the frame-level and clip-level object query signals to extract refined object representations, and applies time-weighted pooling to frame-level queries to suppress low quality object queries. Experimental results demonstrate that our XFRT surpasses current SOTA methods in all metrics with large margins on two popular benchmarks, A2D-Sentences and JHMDB-Sentences datasets.
Shuqian Xie | 14 April 2023 Knowledge-Based Multi-Agent Deep Reinforcement Learning for Algorithmic Trading
Speaker: Shuqian Xie
Title: Knowledge-Based Multi-Agent Deep Reinforcement Learning for Algorithmic Trading
Date/Time: 14 Apr. 2023, Friday, 10:00 AM - 11:00 AM
Abstract: Deep reinforcement learning (DRL) has been applied to solve complex problems in a variety of domains, including algorithm trading. Traditional trading strategies, such as mean reversion and momentum, have been widely used in practice, gaining empirical success but with diminishing and more volatile returns. Nowadays, these single strategies could hardly be profitable under dynamic market conditions. In order to utilize the advantages of existing strategies and overcome their limitations, we propose a knowledge-based multi-agent deep reinforcement framework for the development of intraday trading strategies. Our DRL agents are designed to improve the base mean reversion and momentum strategies and combine both to make trading decisions under different circumstances. This framework uses features like technical indicators and discrete wavelet transformation to capture price patterns. Additionally, to avoid overfitting, we apply a validation-feedback mechanism in our empirical experiments on a S\&P 500 ETF (SPY) to improve learning results. Overall, our proposed framework represents a promising step towards a more effective method in DRL for algorithmic trading.
CANCELED - Saarthak Kapse | 28 April 2023 Domain-driven Approaches for Self Supervised Learning in Computational Pathology
Speaker: Saarthak Kapse
Title: Domain-driven Approaches for Self Supervised Learning in Computational Pathology
Date/Time: 28 Apr. 2023, Friday, 10:00 AM - 11:00 AM
Abstract: Computational techniques have ushered in a new era in the field of pathology by enabling high throughput and intelligent analysis of pathology slides. In this webinar, we will discuss the enhancement of representation learning techniques in computational pathology. Attendees will gain valuable insights into the unique challenges involved in working with gigapixel digital pathology images, as well as their distinctive differences from natural imaging. Moreover, we will delve into one of the most fascinating recent advances in the field of representation learning, namely Self-Supervised Learning (SSL), and highlight its potential for revolutionizing the way we approach computational pathology. In addition, this presentation will shed light on the potential pitfalls of directly applying SSL methods, originally proposed for natural imaging, to digital pathology. The session will culminate with an in-depth presentation of our group's current progress in addressing the challenges and proposing innovative domain-driven and interpretable solutions. By participating in this session, participants will acquire a profound understanding of the substantial benefits of domain-driven approaches for deep learning in computational pathology, as well as the latest research in this rapidly advancing field. These advancements have the potential to improve patient care by enabling more precise and personalized diagnoses and treatment decisions. Furthermore, computational pathology has opened up new opportunities for research, education, and quality assurance in pathology, paving the way for a data-driven approach to pathology practice that holds promise for the future of precision medicine.
Fall 2022 Semester
Eesh Naik, Som Naik | 9 September 2022 | Inflation Uncertainty: ETF Risk Model, Structural Change, and Breakeven Inflation & TIPS ETF: An explanatory model using CPI
Speaker: Eash Naik, Som Naik
Date/Time: 9 Sep. 2022, Friday, 10:00 AM - 11:00 AM
Abstract: Inflation Uncertainty: ETF Risk Model, Structural Change, and Breakeven Inflation: We present a predictive risk model for a popular Treasury Inflation Protected Securities (TIPS) ETF. The model is based on ARMA-GARCH and a heavy-tailed volatility model. Its assessment based on standard VaR, CVaR, and Kolmogorov-Smirnov statistics is very encouraging. We also study structural breaks in the CPI-based inflation rate. The structural breaks correlate with key inflation related external events. Inflation expectations are expressed through the breakeven inflation (BEI) rate. We infer distinctive market motivations of TIPS investors based on BEI expectations across TIPS maturities.
TIPS ETF: An explanatory model using CPI: This paper investigates the relationship between ETFs composed of Treasury Inflation Protected Securities (TIPS) and inflation as indicated by the CPI. The iShares TIPS ETF and the Consumer Price Index for All Urban Consumers (CPIAUCSL) metric are selected for analysis. Our main result is to establish the rationale which governs the behavior of participants in this market. Strong upwards or strong downwards movements of inflation, or the absence of either, are the major factors governing participants’ behavior. This insight leads to the identification of three distinct regimes of TIPS ETF price movements during varying types of shocks in the CPIAUCSL. A model is then constructed using insights from the three regimes. The model is tested by out-of-sample data and provides an excellent agreement with observations. An R-squared value of 0.989 is achieved when the model is trained on the first half of the data. The data and the model both suggest an inverse relationship between iShares TIPS ETF price data and the CPIAUCSL metric during strong price shocks.
Zhikang Dong | 23 September 2022 | Physics Informed Neural Networks with Temporal Changepoints in the Dynamics
Speaker: Zhikang Dong
Title: CP-PINNs: Changepoints Detection in PDEs using Physics Informed Neural Networks with Total-Variation Penalty
Date/Time: 23 Sep. 2022, Friday, 10:00 AM - 11:00 AM
Abstract: We consider the inverse problem for the Partial Differential Equations (PDEs) such that the parameters of the dependency structure can exhibit random changepoints over time. This can arise, for example, when the physical system is either under malicious attack (e.g., hacker attacks on power grids and internet networks) or subject to extreme external conditions (e.g., weather conditions impacting electricity grids or large market movements impacting valuations of derivative contracts). For that purpose, we employ Physics Informed Neural Networks (PINNs) -- universal approximators that can incorporate prior information from any physical law described by a system of PDEs. This prior knowledge acts in the training of the neural network as a regularization that limits the space of admissible solutions and increases the correctness of the function approximation. We show that when the true data generating process exhibits changepoints in the PDE dynamics, this regularization can lead to a complete miss-calibration and a failure of the model. Therefore, we propose an extension of PINNs using a Total-Variation penalty which accommodates (multiple) changepoints in the PDE dynamics. These changepoints can occur at random locations over time, and they are estimated together with the solutions. We propose an additional refinement algorithm that combines changepoints detection with a reduced dynamic programming method that is feasible for the computationally intensive PINNs methods, and we demonstrate the benefits of the proposed model empirically using examples of different equations with changes in the parameters. In case of no changepoints in the data, the proposed model reduces to the original PINNs model. In the presence of changepoints, it leads to improvements in parameter estimation, better model fitting, and a lower training error compared to the original PINNs model. Link: https://arxiv.org/abs/2208.08626
Benjamin Larah | 7 October 2022 | Modeling Your Future Path: A Perspective on a Quant Finance Career
Speaker: Benjamin Larah
Title: Modeling Your Future Path: A Perspective on a Quant Finance Career
Date/Time: 7 Oct. 2022, Friday, 10:00 AM - 11:00 AM
Abstract: Ben Larah, Senior Manager at PwC, will speak about his quantitative finance career journey. He will provide insights around how models are used in practice throughout the financial industry, and share perspectives on the evolution of skills needed to further your quantitative finance career.
Dimitri Bianco | 21 October 2022 | Quant Career Landscape Presentation
Speaker: Dimitri Bianco
Title: Quant Career Landscape Presentation
Date/Time: 21 Oct. 2022, Friday, 10:00 AM - 11:00 AM
Abstract: Sell Side, Buy Side, Crypto, and Fintech. Understanding the quantitative finance landscape, current roles, and the skills needed to built a long term career. Insights and perspective from a head of quant risk and research as well as a discussion on resumes and interviews.
Affiliation: Agora Data
Speaker Bio Dimitri Bianco is currently the Head of Quantitative Risk and Research at Agora Data. He received his bachelors degree in Finance from Washington State University and his Masters of Applied Economics from the University of Michigan. His career has been focused on risk management for eight years working at both regional and global banks doing model development, model validation, model implementation, and internal audit. He has covered credit, operations, market, and regulatory risks across the firms with a focus in time-series. He is also an industry disruptor pushing for an academic approach to using both statistical and machine learning models to solve problems in finance. His current role in fintech is to bring about rigor to modeling methods which provide new technology to the finance industry. He also runs the largest YouTube channel and podcast focused solely on quantitative finance with over 2 million views and nearly 25,000 subscribers. Much of his focus is on career development from students just starting out to more senior positions looking for new opportunities. His life experiences and relationships with both universities and practitioners provides a unique perspective not found elsewhere.
Weichuan Deng | 4 November 2022 | Dynamic Financial Factors Model
Speaker: Weichuan Deng
Title: Dynamic Financial Factors Model
Date/Time: 4 Nov. 2022, Friday, 10:00 AM - 11:00 AM
Abstract: We consider the problem of estimating a regression problem such as dynamic financial factor model where the contribution of the individual factors evolves smoothly over time. In this general setup under proper canonical scaling that ensures functional spaces embedding, we show that the minimax risk of the estimator with total variation regularization is lower than the minimax risk of any linear smoother. Encouraged by these results we develop primal-dual optimization algorithm for fitting the proposed model. Further extensions to local adaptivity, potential curse of dimensionality, and links to deep neural networks will be discussed.
Xiaoqi Dong | 18 November 2022 | Deep Hedging with Regularization
Speaker: Xiaoqi Dong
Title: Deep Hedging with Regularization
Date/Time: 18 Nov. 2022, Friday, 10:00 AM - 11:00 AM
Abstract: Deep hedging is referred to as deep reinforcement machine learning methods that hedges portfolios of derivatives in the presence of market frictions. To stablize the hedging paths, we consider a regularized deep hedging method which adds L2 panelty to the convex risk measure of the portfolio. Our current studies show that the regularized hedging path has less variation than un-regularized hedging path and the induced transac- tion cost is also reduced. (This is a work in progress)
Spring 2022 Semester
Konstantin Kalinchenko | 11 February 2022 | Career in Data Science and Quantitative Finance
Speaker: Konstantin Kalinchenko
Title: Career in Data Science and Quantitative Finance
Date/Time: 11 Feb. 2022, Friday, 10:00 AM - 11:00 AM
Abstract: We will discuss the strategy that a graduate with determination to pursue a career in data intensive profession should follow. We will talk about the landscape of opportunities in various industries, skills that are currently in demand, and what would be the optimal allocation of efforts while you are a student.
Speaker Bio:Dr. Konstantin Kalinchenko has over 12 years of professional experience in various roles concentrated in applications of Statistics, Optimization and Risk Management in Banking, Trading and Data Science Consulting. He currently works for private equity firm Cerberus Capital Management, in its Cerberus Technology Solutions consulting subsidiary. Previously, he was a Vice President in Trading Analytics and Risk Management at hedge fund WorldQuant LLC, a Trading Associate at Deutsche Bank, and Internal Auditor at Sberbank. He defended his PhD dissertation "Optimization with Generalized Deviation Measures in Risk Management" at University of Florida and holds a Specialist degree in Mathematics from M.Lomonosov Moscow State University.
Rui Ding | 25 February 2022 | Risk Sensitivity and Model Uncertainty in Sequential Decision Making
Speaker: Rui Ding
Title: Risk Sensitivity and Model Uncertainty in Sequential Decision Making
Date/Time: 25 Feb. 2022, Friday, 10:00 AM - 11:00 AM
Abstract: In this work we study sequential decision making problems under uncertainty. In particular we are concerned with risk-sensitive MDPs, distributionally robust MDPs where the model parameters are unknown a priori and specified through uncertainty sets, and relevant reinforcement learning algorithms. We highlight a deep connection between risk sensitivity and model uncertainty. This work is two-fold. First, we study CVaR optimization for MDPs and connections with distributionally robust MDPs. The standard CVaR MDP problem can be reformulated through an augmented space where the problem can be interpreted as a distributionally robust MDP with nature playing as an adversary. We provide a better structural formulation using a sufficient statistic to be the augmented state in our value iteration algorithm, hence resolving the possible ambiguity in identifying the assigned risk state. There is a strong relation between risk-sensitive MDPs and distributionally robust MDPs where the uncertainty sets are specified by confidence balls defined through some statistical distances. A particular robust MDP problem under R-contamination uncertainty sets has an interesting connection with a specific nested mean-CVaR mixed criterion MDP. Second, we discuss recent results on the family of f-divergence induced coherent risk measures that draws a direct connection between risk measures and distributional robustness. Building on this new family of risk measures and their properties, we demonstrate equivalence between a class of distributionally robust MDP problems based on statistical distance/divergence uncertainty sets and their corresponding risk sensitive MDPs based on nested conditional construction of f-divergence induced coherent risk measures. In particular, we propose to use the squared Hellinger distance for epistemic uncertainty sets and propose to study the Hellinger robust MDPs through those perspectives. Finally, we discuss some problems from other domains of reinforcement learning that make important use of trust region type methods, which share a similar flavor as the distributional robustness problems in previous sections.
Eric Werneburg | 25 March 2022 | Training Neural Networks Using Reproducing Kernel Space Interpolation
Speaker: Eric Werneburg
Title: Training Neural Networks Using Reproducing Kernel Space Interpolation
Date/Time: 25 Mar. 2022, Friday, 10:00 AM - 11:00 AM
Abstract: We introduce and study the theory of training neural networks using interpolation techniques from reproducing kernel Hilbert space theory. We generalize the method to Krein spaces, and show that widely-used neural network architectures are subsets of reproducing kernel Krein spaces. We introduce the concept of “associated Hilbert spaces” of such conventional neural networks. Using such machinery results in networks with the same expressivity, but which tend to generalize better after being trained. Next, we introduce Agler’s theorem in the context of neural network theory to show that there is one activation function, the expressivity of which is superior to all other desirable activation functions. Finally, we show the successful application of our theory in the field of neurourology and urodynamics.
Yuhang Liu and Weihao Wang | 8 April 2022 | On the Effectiveness of Non-Pharmaceutical Interventions for COVID-19
Speaker: Yuhang Liu and Weihao Wang
Title: On the Effectiveness of Non-Pharmaceutical Interventions for COVID-19
Date/Time: 8 Apr. 2022, Friday, 10:00 AM - 11:00 AM
Abstract: Worldwide, governments imposed a wide range of non-pharmaceutical interventions (NPIs) in the wake of the COVID-19 pandemic. Two years later today, pandemic fatigue has set in among the world’s population as the virus attack continues in waves. To help governments contain the pandemic more effectively and to ease the burden on the population, we examined the effectiveness of individual NPI among the 42 states in the US where the death count exceeded 100 during the first wave of the COVID-19 pandemic (February 1 to June 15, 2020). Two types of analyses were performed. Firstly, a prototypical Bayesian hierarchical model is employed to estimate the effectiveness of 5 commonly imposed NPIs in the US, including gathering restriction, restaurant capacity restriction, business closure, school closure, and stay-at-home. Secondly, the effectiveness of facemask mandate, the most controversial policy among states, is studied through counterfactual modeling, a variant of the prototypical Bayesian hierarchical model.
El Mehdi Ainasse | 22 April 2022 | Multiple Changepoint Detection in Latent Signals and Processes
Speaker: El Mehdi Ainasse
Title: Multiple Changepoint Detection in Latent Signals and Processes
Date/Time: 22 Apr. 2022, Friday, 10:00 AM - 11:00 AM
Abstract: This work introduces a new method for detecting change-points in latent signals indirectly using consistent estimators with arbitrary rates and under a general class of heavy-tailed noise (sub-Weibull). Following the LSTV-LARS algorithm introduced by Leduc-Harchaoui (2010), we use a least-squares criterion with an L1 penalty. We show that despite not using LSTV on the underlying signal (which is assumed to be observed in the case of Leduc-Harchaoui) but using it on the estimator instead, our approach consistently estimates the breakpoint locations and the corresponding underlying latent signal. We also show that our indirect method and the direct approach are, in fact, asymptotically equivalent—both for the breakpoint location estimates and for the estimates of the underlying signal. Our empirics demonstrate that the method performs well even if the breakpoint location is close to the end of the sample and has been used to detect change-points in the mean, the variance, the mean, and the variance simultaneously, as well as the distribution. We will briefly touch upon how this method can be extended, through the introduction of kernels, to a more general functional-analytic setting that is suitable for various other applications.
Fall 2021 Semester
Teng Chen | 10 September 2021 | Tail Index Estimation Based on CVaR
Speaker: Teng Chen
Title: Estimation of Heavy Tails
Date/Time: 10 Sep. 2021, Friday, 10:00 AM - 11:00 AM
Abstract: In extreme value theory, the tail index is a critical measure for assessing the heavy-tailed behavior of a distribution. In this talk, we propose a new class of Pickands-type estimators based on conditional value-at-risk (CVaR) for the tail index. The CVaR-based estimators not only inherit the universal consistency, the location and scale invariant properties of Pickands estimator but also significantly improve the asymptotic efficiency and reduce the sensitivity to the choice of the intermediate order statistics. We prove the weak and strong consistency, and the asymptotic normality of these estimators under quite general conditions. A detailed investigation of the asymptotic behavior of the estimators in the family is carried out in order to identify which members of the family perform optimally. A simulation study involving a wide range of distributions shows the CVaR-based estimators have good finite-sample performance and compare favorably with the other estimators.
Jiaju Miao | 24 September 2021 | Sector Rotation Strategy via Machine Learning
Speaker: Jiaju Miao
Title: Sector Rotation Strategy via Machine Learning
Date/Time: 24 Sep. 2021, Friday, 10:00 AM - 11:00 AM
Abstract: Asset-specific factors have been widely used to explain financial returns and measure asset-specific risk premia. In this paper, we employ these factors in various machine learning models to measure sector risk premia. We initially start with a comparison of the prediction of different models and demonstrate large economic gains from using machine learning for sector forecasting. We develop an assembling algorithm that combines different models based on the history of their performance, and we prove that the risk premia of the resulting meta-algorithm are not much worse than the risk premia of the infeasible optimal assembling. The resulting meta-strategy is used for portfolio investment that substantially outperforms the market.
Qinyun Zhao | 8 October 2021 | Learning and control of time-varying linear quadratic regulator
Speaker: Qinyun Zhao
Title: Learning and control of time-varying linear quadratic regulator
Date/Time: 8 Oct. 2021, Friday, 10:00 AM - 11:00 AM
Abstract: Economic agents are hard to obtain complete information about all the parameters which could affect the payoffs that they receive. However, they could get feedback from observing the rewards of their actions. There is a voluminous literature on learning and control with unknown parameters. In this talk, we first introduce the work in Wieland's paper about his numeric method to get optimal control in a linear process with unknown parameters. After that, I would like to show my on-going work of applying a more efficient method, rollout algorithm to obtain approximate optimal control under more complicate time-varying environments.
Xiaoqi Dong | 22 October 2021 | Survey on multi-agent reinforcement learning
Speaker: Xiaoqi Dong
Title: Survey on multi-agent reinforcement learning
Date/Time: 22 Oct. 2021, Friday, 10:00 AM - 11:00 AM
Abstract: In recent years, reinforcement learning (RL) has been witnessed to have magnificent advances. Most of the RL real-world applications, however, involve the participation of more than one agent, and fall into the realm of multi-agent RL (MARL). Although multi-agent learning (MAL) was first discussed in 1999 and is relatively less popular in 2000s, due to advances in single-agent RL (SARL) techniques and improvements of computation performance, this realm has recently re-merged. In this survey, we pro- vide a selective overview of algorithms in MARL. In specific, we review the algorithms in two representative frameworks, Markov games and extensive-form games, in accordance with the types of learning goals, which are fully cooperative, fully competitive, and a mix of the two. (This talk is a review of Zhang, Kaiqing, Zhuoran Yang, and Tamer Başar. "Multi-agent reinforcement learning: A selective overview of theories and algorithms." Handbook of Reinforcement Learning and Control(2021): 321-384).
Ryan Kaufman and Prof. James Glimm | 5 November 2021 | GA1.2: An Intraday and Overnight Risk Model and Interest Rate Risk
Speaker: Ryan Kaufman and Prof. James Glimm
Title: GA1.2: An Intraday and Overnight Risk Model and Interest Rate Risk
Date/Time: 5 Nov. 2021, Friday, TBD
Abstract: Both daily and intraday risk models miss one of the key elements of a day's risk: the overnight jump. Intraday risk models will underestimate the day's risk when using time series analysis without a model for the overnight step, during which new information becomes available to traders, but prices freeze, a feature not captured in the time series representation of the data. Daily risk models will also underestimate the risk. Daily time series does capture the overnight step within the data, but averages it in with the risk of the whole day. Interest rate forecasting also comes with some caveats for modeling, most notably is the effect of political actions. We incorporate this into our model by including information about the present and future federal reserve rate into the model for bond prices, which is used to calculate risk. We show models for both of these phenomena and present some results.
Greeshma Balabhadra | 19 November 2021 | Breakpoints in High Frequency Volatility
Speaker: Greeshma Balabhadra
Title: Breakpoints in High Frequency Volatility
Date/Time: 19 Nov. 2021, Friday, 10:00 AM - 11:00 PM
Abstract: We introduce two new high-frequency volatility estimators that account for possible breakpoints in the spot volatility process. They are l1-penalized versions of classical estimators—the quadratic variation, and, jump robust version of it, bipower variation. We show that in the presence of a mean-square error of order op(1) achieved by these classical estimators, detecting breakpoints using the volatility estimator is asymptotical equivalent to detecting them using the infeasible (latent) volatility path. The proposed estimators are evaluated in simulations and on real data. They are fast in computations, and they accurately detect breakpoints that are close to the end of the sample—both properties are very desirable for financial applications. In terms of out-of-sample volatility prediction, qualitatively, the new estimators provide more smooth and realistic forecasts; quantitatively, they outperform the aforementioned competitors and their extensions at various frequencies and forecasting horizons.
Jin Huang | 3 December 2021 | Convergence analysis of Matural policy gradient algorithms
Speaker: Jin Huang
Title: Convergence Analysis of Natural Policy Gradient Algorithms
Date/Time: 3 Dec. 2021, Friday, 10:00 AM - 11:00 AM
Abstract: When solving the problem of reinforcement learning, we often use optimization methods such as gradient descent. In this study, we are committed to studying the convergence of the Natural Policy Gradient under multiple iterations. Besides, we continue to discuss the possibility of convergence based on Natural Actor-Critic algorithm. The purpose of the research is to achieve faster convergence and theoretically establish the premise of high algorithm efficiency.
Spring 2021 Semester
Mr. Gabriel Mihalache | 12 February 2021 | Sustainable Debt with Long Run Risk
Speaker: Gabriel Michalache
Title: Sustainable Debt with Long Run Risk
Date/Time: 12 Feb. 2021, Friday, 10:00 AM - 11:00 AM
Abstract: We propose a parsimonious framework for the quantitative evaluation of sustainable debt in emerging markets, by embedding rich fiscal rules and a pricing kernel consistent with key stylized facts, as in Bansal and Yaron (JF, 2004), in the slow-moving debt crisis model of Lorenzoni and Werning (AER, 2019). The model can replicate the importance of a common global factor in spreads and the slow response of primary deficits to debt overhang. The framework supports the design of robust fiscal rules.
Speaker Bio: Gabriel Mihalache is an Assistant Professor of Economics at Stony Brook University since 2016. He was awarded a MSc in Applied Economics in Statistics by Clemson University in 2010 and a PhD in Economics in 2016 by the University of Rochester. His work addresses the causes and consequences of sovereign default risk for the maturity structure of sovereign debt, capital accumulation, and monetary policy.
Mr. Kevin Maritato | 26 February 2021 | An Introduction to Buffered Probability Distribution Functions
Speaker: Kevin Maritato
Title: An Introduction to Buffered Probability Distribution Functions
Date/Time: 26 Feb. 2021, Friday, 10:00AM - 11:00AM
Abstract: In this paper we introduce the concept of Buffered Probability Distribution Functions (bPDFs), as the derivative of the inverse of the Conditional Value at Risk (CVaR). We first explore the connection between this value and risk measures such as the Buffered Probability of Exceedance (bPoE). Then we describe three means of calculating the bPDF for a distribution, depending on what is known about the distribution. For functions with a closed-form formula for bPoE, we derive closed-form formulae for bPDF. We also examine using these formulae for parameter estimation using the maximum likelihood method. We then describe a method for deriving a formula for bPDF based on a numerical bPoE (calculated using Portfolio Safeguard software) when there is a closed-form formula for CVaR but no formula for bPoE. Finally, we give a method for numerically calculating bPDF for an empirical distribution, and compare the results of this method to those given by the other methods for known distributions.
Haoran Jiang| 26 March 2021 | Modeling and computation of multi-step batch testing for infectious diseases
Speaker: Haoran Jiang
Title: Modeling and computation of multi-step batch testing for infectious diseases
Date/Time: 26 Mar. 2021, Friday, 10:00AM - 11:00 AM
Abstract: We propose a mathematical model based on probability theory to optimize COVID-19 testing by a multi-step batch testing approach with variable batch sizes. This model and simulation tool dramatically increase the efficiency and efficacy of the tests in a large population at a low cost, particularly when the infection rate is low. The proposed method combines statistical modeling with numerical methods to solve nonlinear equations and obtain optimal batch sizes at each step of tests, with the flexibility to incorporate geographic and demographic information. In theory, this method substantially improves the false positive rate and positive predictive value as well. We also conducted a Monte Carlo simulation to verify this theory. Our simulation results show that our method significantly reduces the false negative rate. More accurate assessment can be made if the dilution effect or other practical factors are taken into consideration. The proposed method will be particularly useful for the early detection of infectious diseases and prevention of future pandemics. The proposed work will have broader impacts on medical testing for contagious diseases in general.
Oluyemi Oyeniran | 9 April 2021 | The Non-Clinical Statistics
Speaker: Oluyemi Oyeniran
Panelists: Fanni Zhang, Jyh-Ming Shoung, Thomas Bradstreet, Wei Zhao (Detail information)
Title: The Non-Clinical Statistics
Date/Time: 9 Apr. 2021, Friday, 10:00 AM - 11:00 AM
Abstract: We will use this opportunity to introduce to the students the drug development process and how non-clinical statistics are involved in each and every step. After the presentation, we hope the students will have a better understanding of different career paths in the pharmaceutics industry.
Mr. Mitch Gao | 23 April 2021 | NIG Process and Its Application in Option Pricing and Interest Rate Models
Speaker: Mr. Mitch Gao
Title: NIG Process and Its Application in Option Pricing and Interest Rate Models
Date/Time: 26 Mar. 2021, Friday, TBD
Abstract: NIG type time-inhomogeneous Levy process, introduced by Barndorﬀ-Nielsen as a Normal variance-mean mixture with an Inverse Gaussian mixing distribution, have greater ﬂexibility and can model a variety of distributions, making this process one of great interest from a mathematical ﬁnance point of view. In this work, we study the NIG option pricing under Esscher transformation and explore its application in term structure of interest rate models.
Yizhou Li | 7 May 2021 | Dynamic management of loan portfolios
Speaker: Yizhou Li
Title: Dynamic management of loan portfolios
Date/Time: 7 May 2021, Friday, 10:00 AM - 11:00 AM
Abstract: Dynamic management of loan portfolio is a very important task of bank. A bank can run its capital to investment loans dynamically by stochastic optimization model based on its constraint of asset and liability. At the first step of this task, we improved the accuracy of loan default prediction from LendingClub, a peer-to-pear lending platform, and this default prediction is considered as a binary classification problem. We propose a two-step training model. This model first utilizes feature-wise spline logistic regression with polynomial function to transform features, and then predicts default by logistic regression. We used metrics including the area under the ROC curve (AUC) and accuracy rate for evaluation of this algorithms, and this has been done both in-sample and out-of-sample. The feature-wise spline regression can also be used for feature selection and demonstrate visually the relationship between probability of default and feature. As a result, rather than using massive features with neural network, random forest or any other machine learning classifiers, a simple logistic regression model with a limited number of features will output the best metrics.
Fall 2020 Semester
Mr. Teng Chen | 11 September 2020 | Classification and Severity Progression Measure of COVID-19 Patients Using Proteomic and Metabolomic Sera
Speaker: Mr. Teng Chen (joint presentation with Prof. Pawel Polak and Prof. Stan Uryasev)
Title: Classification and Severity Progression Measure of COVID-19 Patients Using Proteomic and Metabolomic Sera
Date/Time: 11 Sep. 2020, Friday, 10:00 - 11:00 AM EST
Zoom Link: https://stonybrook.zoom.us/j/333315931?pwd=WndYa2thL2lOWjJobm9xd3djc0JXZz09
Abstract: Early detection and effective treatment of severe COVID-19 patients remain one of the major challenges during the current pandemic. Analysis of molecular changes in blood samples of severe patients is one of the promising approaches to this problem. From 75 most relevant proteomic and metabolomic factors selected by Shen et al. (2020), we identify several pairs of factors (some of them after additional nonlinear spline transformation) that are highly effective in classifying severe COVID-19 cases. The performance of these pairs is evaluated in-sample, in a cross-validation exercise, and in an out-of-sample analysis on an independent dataset. Our findings can help medical experts to identify small groups of biomarkers that can be used to construct a cost-effective, short-term test for patients screening and a measure of severity progression.
Mr. Pengzhan Guo | 9 October 2020 | Customizable Career Path Recommendation with Multi-Criteria Stochastic Optimization
Speaker: Mr. Pengzhan Guo
Title: Customizable Career Path Recommendation with Multi-Criteria Stochastic Optimization
Date/Time: 9 October 2020, Friday, 10:00 - 11:00 AM EST
Zoom Link: https://stonybrook.zoom.us/j/98544332907?pwd=UHNocExQeXB5blpLajdmZ0h2RVpBQT09
Abstract: Career mobility forecasting and recommendation are important research topics in talent management and people analytics. While existing models mainly focus on short-term one-period recommendation and prediction for job seekers, the long-term customizable career path recommendation (CPR) is a topic that has not been sufficiently investigated. In this project, we propose a generalized model of CPR and investigate related mathematical and economic characteristics from a long-term customizable perspective. The new objective function is capable of delivering personalized long-term career plans while upholding properties corresponding to three common facts among existing literature on job mobility. We then develop an efficient and effective searching algorithm to achieve the optimal solution of CPR based on simulated annealing and Markov chain techniques. We not only show the effectiveness of our method theoretically but also compare it to three different versions of the greedy method that includes the current state-of-the-art method empirically in addressing similar problems. From simulations based on a large real-world dataset, we show consistent results reaffirming the superior performance of our method in recommending optimal career paths based on user-defined criteria.
Mr. Yuanchen Huang | 23 October 2020 | Time Varying Parameter Selection with Spike and Slab Prior
Speaker: Mr. Yuanchen Huang
Title: Time Varying Parameter Selection with Spike and Slab Prior
Date/Time: 23 October 2020, Friday, 10:00 - 11:00 AM EST
Zoom Link: https://stonybrook.zoom.us/j/98544332907?pwd=UHNocExQeXB5blpLajdmZ0h2RVpBQT09
Mr. Ziheng Chen | 6 November 2020 | On Reinforcement Learning and Compressed Sensing
Speaker: Mr. Ziheng Chen
Title: On Reinforcement Learning and Compressed Sensing
Date/Time: 6 November 2020, Friday, 10:00 - 11:00 AM EST
Zoom Link: https://stonybrook.zoom.us/j/98544332907?pwd=UHNocExQeXB5blpLajdmZ0h2RVpBQT09
Xiaoqi Dong | 20 November 2020 | Weighted reduced rank analysis of time varying cointegration vector
Speaker: Xiaoqi Dong
Title: Weighted reduced rank analysis of time varying cointegration vector
Date/Time: 20 November 2020, Friday, 10:00 - 11:00 AM EST
Zoom Link: https://stonybrook.zoom.us/j/333315931?pwd=WndYa2thL2lOWjJobm9xd3djc0JXZz09