Model averaging has become a popular method of estimation, following increasing evidence that model selection and estimation should be treated as one joint procedure. Weighted‐average least squares (WALS) is a recent model‐average approach, which takes an intermediate position between frequentist and Bayesian methods, allows a credible treatment of ignorance, and is extremely fast to compute. We review the theory of WALS and discuss extensions and applications. 相似文献
Bayesian model averaging has become a widely used approach to accounting for uncertainty about the structural form of the model generating the data. When data arrive sequentially and the generating model can change over time, Dynamic Model Averaging (DMA) extends model averaging to deal with this situation. Often in macroeconomics, however, many candidate explanatory variables are available and the number of possible models becomes too large for DMA to be applied in its original form. We propose a new method for this situation which allows us to perform DMA without considering the whole model space, but using a subset of models and dynamically optimizing the choice of models at each point in time. This yields a dynamic form of Occam׳s window. We evaluate the method in the context of the problem of nowcasting GDP in the Euro area. We find that its forecasting performance compares well with that of other methods. 相似文献
Objective: The objective of this study was to assess the cost of hypoglycemic events among insulin-treated patients with diabetes and the potential cost savings to a hypothetical US health plan and employer of reducing hypoglycemic events with a device intervention.
Methods: A cost-calculator model was developed to estimate the direct costs of hypoglycemic events, accounting for diabetes type, age, and event severity. Model inputs were derived from published incidence rates of hypoglycemic events and direct medical costs. Assumed intervention efficacy was based on published studies of an emerging technology which yielded 72.2% (LGS Trial; ACTRN12610000024044) and 31.8% (ASPIRE Trial; NCT01497938) reductions in severe and non-severe hypoglycemic events, respectively. Model outcomes—including the number of severe (requiring medical assistance) and non-severe events, and direct/indirect medical costs (excluding intervention costs)—were evaluated over a 1-year period for a hypothetical health plan and employer perspectives.
Results: In a health plan with 10 million enrollees, patients without the intervention would have experienced 0.09 and 14.60 severe and non-severe hypoglycemic events per patient per year (PPPY), respectively (vs 0.02 severe and 9.96 non-severe events with the intervention). This translated into total direct medical cost savings of $45 million ($177 PPPY) for the health plan. For an employer with 100,000 employees, the intervention would have yielded additional savings of $492 PPPY in indirect costs.
Conclusion: Insulin-treated patients experience hypoglycemic events, which are associated with substantial direct and indirect medical costs. The cost savings of reducing hypoglycemic events need to be weighed against the costs of using diabetes device interventions. 相似文献
This study examines the stock price crash risk for a sample of firms that disclosed internal control weaknesses (ICW) under Section 404 of the Sarbanes‐Oxley Act (SOX). We find that in the year prior to the initial disclosures, ICW firms are more crash‐prone than firms with effective internal controls. This positive relation is more pronounced when weakness problems are associated with a firm's financial reporting process. More importantly, we find that stock price crash risk reduces significantly after the disclosures of ICWs, despite the disclosure itself signalling bad news. The above results hold after controlling for various firm‐specific determinants of crash risk and ICWs. Using an ICW disclosure as a natural experiment, our study attempts to isolate the presence effect of undisclosed ICWs from the initial disclosure effect of internal control weakness on stock price crash risk. In so doing, we provide more direct evidence on the causal relation between the quality of financial reporting and stock price crash risk. 相似文献