Mohammad A. Chaudhary, Haitao Chu, Joseph C. Cappelleri
{"title":"Evaluating Uncertainties in Health Economic Models: A Review and Guide","authors":"Mohammad A. Chaudhary, Haitao Chu, Joseph C. Cappelleri","doi":"10.1002/asmb.70044","DOIUrl":"https://doi.org/10.1002/asmb.70044","url":null,"abstract":"<div>\u0000 \u0000 <p>In health economics, decision-makers rely on models to assess the cost-effectiveness of healthcare interventions and guide resource allocation. Health Technology Assessment (HTA) agencies employ cost-effectiveness models to determine the approval and market access of new therapies within their respective jurisdictions. Health economists use quantitative techniques to synthesize clinical, epidemiological, and economic data to model the costs and effectiveness of a new drug compared to the current standard of care over the lifetime of the patients. These models frequently integrate a wide range of assumptions and data inputs from various sources, which renders them vulnerable to a significant level of uncertainty. Economic models commonly confront multiple forms of uncertainty, such as stochastic uncertainty (first-order), which differs from parameter uncertainty (second-order), as well as the presence of heterogeneity within patient populations. Additionally, structural uncertainty related to the model itself adds another layer of complexity. Uncertainty assessment is essential in model-based health economic evaluations that inform regulatory and reimbursement decisions. Understanding these sources of uncertainty, taking steps to minimize their impact, and analyzing, quantifying, and reporting these inherent uncertainties are crucial for ensuring that health economic models provide robust and reliable insights for effective decision-making. This article examines different types of uncertainty in health economic models and methods to analyze and quantify them, offering practical guidelines with examples from recent literature.</p>\u0000 </div>","PeriodicalId":55495,"journal":{"name":"Applied Stochastic Models in Business and Industry","volume":"41 5","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145224113","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Beyond Randomization: Design and Analysis of Discrete Choice Experiments in the Presence of Profile Order Effects Within Choice Sets","authors":"Yicheng Mao, Roselinde Kessels, Robert Mee","doi":"10.1002/asmb.70043","DOIUrl":"https://doi.org/10.1002/asmb.70043","url":null,"abstract":"<p>Discrete Choice Experiments (DCEs) investigate the attributes that affect individual choices among different options and are widely applied across numerous fields. Past DCEs provide clear evidence that the presentation order of the profiles within a choice set can impact the respondents' choices. Ignoring such order effects can produce severely biased estimates, as we illustrate using a product packaging DCE performed for Procter & Gamble in Mexico. Currently, the most common approach to address profile order effects is to randomize the profile order. While this method is relatively easy to implement in online surveys, it can be considerably cumbersome in offline experimental settings. To address this, we suggest incorporating an order covariate in the model to measure the effect of profile order, and propose a Bayesian optimal Balanced Profile Order Design (BPOD) that accounts for this order effect. Our simulation experiments reveal that our Bayesian optimal BPOD achieves accurate parameter estimates comparable to those obtained through randomization in both the multinomial logit model and the panel mixed logit model. Beyond DCEs, this design strategy contributes to broader efforts in experimental design by providing a generalizable framework for addressing structural sources of bias in applied statistical research.</p>","PeriodicalId":55495,"journal":{"name":"Applied Stochastic Models in Business and Industry","volume":"41 5","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/asmb.70043","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145101878","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Thanoj K. Muddana, Komal S. R. Bhimireddy, Anandamayee Majumdar, Rangan Gupta
{"title":"Forecasting Gold Returns Volatility Over 1258–2023: The Role of Moments","authors":"Thanoj K. Muddana, Komal S. R. Bhimireddy, Anandamayee Majumdar, Rangan Gupta","doi":"10.1002/asmb.70042","DOIUrl":"https://doi.org/10.1002/asmb.70042","url":null,"abstract":"<div>\u0000 \u0000 <p>We analyze the role of leverage, lower and upper tail risks, skewness, and kurtosis of real gold returns in forecasting its volatility over the annual data sample from 1258 to 2023. To conduct our forecasting experiment, we first fit Bayesian time-varying parameters quantile regressions to real gold returns, under six alternative prior settings, to obtain the estimates of volatility (as inter-quantile range), lower and upper tail risks, skewness, and kurtosis. Second, we forecast the derived estimates of conditional volatility using the information contained in leverage of gold returns, tail risks, skewness, and kurtosis using recursively estimated linear predictive regressions over the out-of-sample periods. We find strong statistical evidence of the role of the moments-based predictors in forecasting gold returns volatility over the short to medium term, i.e., till 1–5-year ahead, when compared to the autoregressive benchmark. Robustness of our main result is also validated based on a shorter sample involving higher-frequency data. Our results have important implications for investors and policymakers.</p>\u0000 </div>","PeriodicalId":55495,"journal":{"name":"Applied Stochastic Models in Business and Industry","volume":"41 5","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145101132","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Robin Kühlem, Daniel Otten, Daniel Ludwig, Anselm Hudde, Alexander Rosenbaum, Andreas Mauthe
{"title":"Backdoor Attacks on DNN and GBDT: A Case Study From the Insurance Domain","authors":"Robin Kühlem, Daniel Otten, Daniel Ludwig, Anselm Hudde, Alexander Rosenbaum, Andreas Mauthe","doi":"10.1002/asmb.70029","DOIUrl":"https://doi.org/10.1002/asmb.70029","url":null,"abstract":"<p>Machine learning (ML) will most likely play a large role in many processes in the future, also in the insurance industry. However, ML models are at risk of being attacked and manipulated. A model compromised by a backdoor attack loses its integrity and can no longer be deemed trustworthy. Ensuring the trustworthiness of ML models is crucial, as compromised models can lead to significant financial and reputational damage for insurance companies. In this work the robustness of Gradient Boosted Decision Tree (GBDT) models and Deep Neural Networks (DNN) within an insurance context is evaluated. Therefore, two GBDT models and two DNNs are trained on two different tabular datasets from an insurance context. Past research in this domain mainly used homogeneous data and there are comparably little insights regarding heterogeneous tabular data. The ML tasks performed on the datasets are claim prediction (regression) and fraud detection (binary classification). For the backdoor attacks different samples containing a specific pattern were crafted and added to the training data. It is shown, that this type of attack can be highly successful, even with a few added samples. The backdoor attacks worked well on the models trained on one dataset but poorly on the models trained on the other. In real-world scenarios the attacker will have to face several obstacles but as attacks can work with very few added samples this risk should be evaluated. Therefore, understanding and mitigating these risks is essential for the reliable deployment of ML in critical applications.</p>","PeriodicalId":55495,"journal":{"name":"Applied Stochastic Models in Business and Industry","volume":"41 5","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/asmb.70029","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145007920","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Pricing Basket Spread Option Under the Correlated Skew Brownian Motions","authors":"Qifeng Zhong, Xingye Yue, Jing Yao","doi":"10.1002/asmb.70040","DOIUrl":"https://doi.org/10.1002/asmb.70040","url":null,"abstract":"<div>\u0000 \u0000 <p>In this article, we propose synthetic analytical approximate pricing formulas for basket and basket spread options within a multidimensional correlated skew Brownian motion framework. For basket options, we derive two analytical approximate pricing formulas by utilizing the partial exact approximation, the moment matching method and convex bounds approximation together and achieve accurate and analytical approximations. For basket spread options, we derive a lower bound approximation using the Bjerksund–Stensland-type approach. Numerical examples demonstrate superior performance with consistent robustness and high precision of our formulas, remarkably maintaining excellent performance for high-dimensional options. We also note that these approximate pricing formulas can serve as powerful control variates for the variance reduction of Monte Carlo simulations.</p>\u0000 </div>","PeriodicalId":55495,"journal":{"name":"Applied Stochastic Models in Business and Industry","volume":"41 5","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144923830","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Directional False Discovery Rate Control in Large-Scale Multiple Testing Under Data Dependence","authors":"Wendong Li, Jianqing Shi, Yi Wang, Dongdong Xiang","doi":"10.1002/asmb.70041","DOIUrl":"https://doi.org/10.1002/asmb.70041","url":null,"abstract":"<div>\u0000 \u0000 <p>Detecting directional signals in multiple testing is crucial to take targeted and effective measures. In this article, we consider the directional multiple testing under the dependence problem within a three-group model. Given the assumption that the observed data are generated according to an underlying three-state hidden Markov model, we develop oracle and data-driven procedures to maximize the expected number of true discoveries (ETD) while controlling the false discovery rates (FDRs) of both alternative states at their nominal levels. It is shown theoretically that the proposed directional multiple testing procedures are valid and have certain optimality properties for directional FDR-control. An extensive numerical study shows that our procedures are significantly more powerful than their competitors since the former can accommodate the dependence structure among hypotheses. The proposed procedures also exhibit high flexibility by allowing different nominal levels for the two alternative states, which is appealing in cases when the false discoveries of different alternative states are not equally important. As a demonstration, the proposed data-driven procedure is applied to learn the transcriptomic characteristics of bronchoalveolar lavage fluid in COVID-19 patients.</p>\u0000 </div>","PeriodicalId":55495,"journal":{"name":"Applied Stochastic Models in Business and Industry","volume":"41 5","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144923789","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Éder S. Brito, Vera L. D. Tomazella, Paulo H. Ferreira, Francisco Louzada
{"title":"Bayesian Analysis of Shared Frailty Models for Repairable Systems Subject to Imperfect Repair","authors":"Éder S. Brito, Vera L. D. Tomazella, Paulo H. Ferreira, Francisco Louzada","doi":"10.1002/asmb.70039","DOIUrl":"https://doi.org/10.1002/asmb.70039","url":null,"abstract":"<div>\u0000 \u0000 <p>Repairable systems, crucial in reliability studies, are characterized by recurrent failure times modeled as counting processes with intensity functions. This paper explores models for these failure times incorporating imperfect repairs, addressing unobserved heterogeneity via shared frailty models. In this context, our approach involves scenarios with general imperfect repairs, which offer a more realistic perspective compared to the minimal or perfect repair assumptions commonly employed in the reliability literature. We propose hierarchical Bayesian methods to estimate parameters, leveraging the Power-Law Process for initial intensities and gamma distributions for frailty terms. Bayesian methods are highly flexible and can accommodate complex shared frailty models that include random effects and dependencies between units. Applying Bayesian inference with gamma and beta distribution priors, coupled with Monte Carlo simulations, provides a robust methodology for estimating unknown parameters and deriving posterior distributions. This flexibility is crucial for capturing the underlying structure of the data in repairable systems with imperfect repairs. Our hierarchical Bayesian framework accommodates multiple systems, providing insights into failure processes and supporting enhanced maintenance strategies. We demonstrate our approach using a real failure times dataset and evaluate its performance through simulation studies, showcasing its applicability and relevance in practical settings.</p>\u0000 </div>","PeriodicalId":55495,"journal":{"name":"Applied Stochastic Models in Business and Industry","volume":"41 5","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144915101","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Rajat Das, Yogesh Mani Tripathi, Liang Wang, Shuo-Jye Wu
{"title":"Inference for Simple Step Stress Accelerated Life Test Model Under Progressively Censored Gompertz Data","authors":"Rajat Das, Yogesh Mani Tripathi, Liang Wang, Shuo-Jye Wu","doi":"10.1002/asmb.70037","DOIUrl":"https://doi.org/10.1002/asmb.70037","url":null,"abstract":"<div>\u0000 \u0000 <p>In this article analysis of a simple step-stress accelerated life test is considered under progressive type-II censoring. A cumulative exposure model is considered when the latent lifetimes of test units follow the Gompertz distribution with different shape parameters and a common scale parameter. We explore the study by estimating all unknown parameters using classical and Bayesian techniques. The model parameters are estimated using maximum likelihood and Bayesian methods. Subsequently, interval estimates are derived based on the observed Fisher information matrix. Bayesian estimates are obtained using squared error and linear exponential loss functions. Subsequently highest posterior density intervals are also constructed. We examine the efficiency of all estimators through simulation studies. Finally, we provide a real-life example in support of the considered model.</p>\u0000 </div>","PeriodicalId":55495,"journal":{"name":"Applied Stochastic Models in Business and Industry","volume":"41 5","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144897464","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Alessandro Albano, Chiara Di Maria, Mariangela Sciandra, Antonella Plaia
{"title":"Causal Forests for Discovering Diagnostic Language in Electronic Health Records","authors":"Alessandro Albano, Chiara Di Maria, Mariangela Sciandra, Antonella Plaia","doi":"10.1002/asmb.70038","DOIUrl":"https://doi.org/10.1002/asmb.70038","url":null,"abstract":"<p>Textual analysis has gained significant interest in medical research, particularly for automated patient diagnosis based on clinical narratives. While traditional approaches often focus on associational methods, this paper explores the application of causal forests to analyze textual data from electronic health records (EHRs), aiming to identify causal relationships between specific words and the likelihood of receiving certain medical diagnoses. Utilizing the MIMIC-III dataset, we assess how linguistic factors influence diagnosis probabilities for three conditions: diabetes, hypothyroidism, and adrenal gland disorders. Our findings reveal significant causal links between certain clinical terms and diagnosis probabilities, emphasizing the potential of causal inference techniques to improve the analysis of language in clinical narratives. Additionally, we uncover heterogeneity in treatment effects, demonstrating that specific words can identify high-risk patient subgroups. This study highlights the importance of integrating causal inference in natural language processing within healthcare settings.</p>","PeriodicalId":55495,"journal":{"name":"Applied Stochastic Models in Business and Industry","volume":"41 5","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/asmb.70038","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144897465","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Reliability Inference in GLFP Models Based on EM Algorithm With Related Application","authors":"Chih-Ying Tai, Tsai-Hung Fan","doi":"10.1002/asmb.70030","DOIUrl":"https://doi.org/10.1002/asmb.70030","url":null,"abstract":"<div>\u0000 \u0000 <p>During the manufacturing processes for the integrated circuit (IC) products, defective units may not be screened out by the quality inspections. The defective units often lead to infant mortality failure in the early stages of operation, while non-defective units will eventually fail due to wear-out failure. The general limited failure population (GLFP) model can be used to describe such a phenomenon in which defective units induce failure affected by both failure mechanisms, but failure of non-defective units is only due to wear-out. Besides, when a failure occurs, it is not known whether it is defective and yet which failure mode causes the failure. This article proposes an EM algorithm along with the missing information principle for the GLFP models under multiply censored Weibull distributions to simplify the maximum likelihood (ML) inference. It resolves the computational instability and provides more accurate reliability inference. With the embedded latent variables, failure mode detection and defect identification are also made for masked data, consequently. Furthermore, the proposed method can be extended to the GLFP models of interval data. The simulation study shows that the proposed method provides more accurate results. Two illustrative examples highlight the feasibility and advantages of the proposed approach.</p>\u0000 </div>","PeriodicalId":55495,"journal":{"name":"Applied Stochastic Models in Business and Industry","volume":"41 4","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144767709","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}