Weighted and quadratic models of choice under uncertainty

This paper extends the weighted and quadratic utility models of choice under risk to the context of choice under uncertainty. An important characteristic of the models is that they admit ‘dynamically consistent’ updating rules.     

The welfare implications of advertising and extension under uncertainty

This paper specifies an adoption model based upon Bayesian learning and exogenous information generation. Formulae for welfare effects are derived and calibrated using Green Revolution agricultural data. The effects of intervention through the dissemination of new information are then estimated numerically. The simulations indicate that gains to intervention can be substantial. Intervening with slowly adopted marginal technologies is as beneficial as intervening with superior technologies. Taken from Shampine [Am. J. Agric. Econ. 2 (1998).], which examined intervention in the presence of learning externalities, the results suggest that if adoption is slow, and information is the primary constraint, the gains to intervention are generally substantial relative to the costs.     

Subsidies under uncertainty: Modeling of input- and output-oriented policies

Agricultural subsidies play an essential role in agricultural and rural development in many developed economies. Countries have implemented agricultural subsidy policies with a focus on food security and environmental protection. Agricultural production is risky and uncertain, influencing the efficiency of agricultural subsidies. This study develops a theoretical framework to analyze the effects of production uncertainties on the efficiency of agricultural subsidy policies under the double constraints of food security and environmental protection. The basic model is investigated under six different conditions, and expanded research also is presented. Our models show that uncertainty, including output, cost, and price uncertainties, and technology conversion efficiency significantly affects the efficiency of agricultural subsidies. Under high technology conversion efficiency, output-oriented subsidies are appropriate for food security and environmental protection goals. Policymakers should take both uncertainty and production efficiency into consideration when choosing between input-oriented and output-oriented subsidy policies.     

The choice and timing of foreign direct investment under uncertainty

This paper sheds new light on why timing and entry mode should be considered simultaneously in the international investment literature. We derive the profit levels at which it is optimal to switch from exporting to setting up a wholly owned subsidiary, creating a joint venture, or licensing production to a local firm. The preferred entry mode depends on uncertainty about future profits, tax differentials between the home and the foreign country, the cost advantages of local firms, institutional requirements, and the degree of cooperation between partners in a joint venture.     

The optimal choice of central bank independence and conservatism under uncertainty

This paper examines the optimal monetary delegation arrangement of central bank independence and conservatism in the presence of uncertainty about the central bank’s output objective. We show that full independence is no longer optimal with uncertain central bank preferences, and that optimal delegation involves the choice of both independence and conservatism. Further, we find that the usual trade-off between independence and conservatism no longer necessarily holds. Consequently, high central bank independence may also require a high level of conservatism.     

Regression analysis on the variation in efficiency frontiers for prevention stage of HIV/AIDS

Abstract

Objectives:

To investigate how the cost effectiveness of preventing HIV/AIDS varies across possible efficiency frontiers (EFs) by taking into account potentially relevant external factors, such as prevention stage, and how the EFs can be characterized using regression analysis given uncertainty of the QALY-cost estimates.

Methods:

We reviewed cost-effectiveness estimates for the prevention and treatment of HIV/AIDS published from 2002–2007 and catalogued in the Tufts Medical Center Cost-Effectiveness Analysis (CEA) Registry. We constructed efficiency frontier (EF) curves by plotting QALYs against costs, using methods used by the Institute for Quality and Efficiency in Health Care (IQWiG) in Germany. We stratified the QALY-cost ratios by prevention stage, country of study, and payer perspective, and estimated EF equations using log and square-root models.

Results:

A total of 53 QALY-cost ratios were identified for HIV/AIDS in the Tufts CEA Registry. Plotted ratios stratified by prevention stage were visually grouped into a cluster consisting of primary/secondary prevention measures and a cluster consisting of tertiary measures. Correlation coefficients for each cluster were statistically significant. For each cluster, we derived two EF equations – one based on the log model, and one based on the square-root model.

Discussion:

Our findings indicate that stratification of HIV/AIDS interventions by prevention stage can yield distinct EFs, and that the correlation and regression analyses are useful for parametrically characterizing EF equations. Our study has certain limitations, such as the small number of included articles and the potential for study populations to be non-representative of countries of interest. Nonetheless, our approach could help develop a deeper appreciation of cost effectiveness beyond the deterministic approach developed by IQWiG.     

Optimal choice of monetary policy instruments under velocity and fiscal shocks

This paper, in the spirit of Poole [Poole, William, 1970. The Optimal Choice of Monetary Policy Instruments in a Simple Macro Model. Quarterly Journal of Economics, 84, 192–216.], studies how differently monetary and fiscal shocks influence the appropriate choice of the monetary policy regime. Velocity shocks are introduced by embedding a stochastic cash-in-advance constraint within the New Keynesian framework. In addition to optimal policy under discretion, three classic rules, interest rate targeting, monetary targeting, and the Taylor rule are ranked under both fiscal and velocity shocks. The non-stationarity of prices under the Taylor rule makes it inferior to the other rules under which prices are stationary. Monetary targeting, by stabilizing aggregate demand under fiscal shocks, outperforms interest rate targeting, while the latter provides a better insulation against velocity shocks. Monetary targeting (under fiscal shocks) and interest rate targeting (under velocity shocks) even outperform the optimal policy under discretion for sufficiently high intertemporal elasticities of consumption substitution.     

基于不确定性视角的PPI与CPI传导关系真相研究

通货膨胀背景下,有关PPI和CPI之间的价格传导关系成为备受关注的热点问题,但现有文献均局限于PPI和CPI均值意义上的格兰杰因果性讨论。事实上,无论从宏观理论出发还是从计量理论出发,PPI和CPI衡量的通胀率的不确定性(inflation uncertainty)及不确定性间的相关性更应引起学术界以及货币当局的关注。鉴于此,我们借鉴Hafner and Herwartz(2004)提出的二阶矩意义的格兰杰因果检验方法,构建Wald形式的统计量对CPI和PPI不确定性因果关系进行检验,发现从通胀不确定性视角来看,PPI和CPI是相互传导的,从传导模式来看,无论以PPIMG还是以CGP"I充当"PPI,均只能在短期影响CPI,而CPI对它们的影响在长短期都是一贯的。由此推断,CPI到PPI方向构成了二者不确定性传导的"系统性"路径,通胀治理须从需求方考虑。     

The cost effectiveness and budget impact of natalizumab for formulary inclusion

Abstract

Background: Crohn's disease (CD) and multiple sclerosis (MS) are debilitating autoimmune diseases, which represent a substantial cost burden in the context of managed care. As a corollary, there is an unmet pharmacotherapeutic need in patient populations with relapsing forms of MS, in addition to populations with moderately to severely active CD with evidence of inflammation who have experienced an inadequate response to other mainstream therapies. The purpose of this study was to analyze the clinical and economic data associated with natalizumab (Tysabri) and to determine the potential impact of its formulary inclusion in a hypothetical health plan.

Findings: Regarding MS, the implemented cost-effectiveness and budget-impact models demonstrated an anticipated reduction in relapse rate of 67% over 2 years, and a total therapy cost of $72,120 over 2 years, equating to a cost per relapse avoided of $56,594. With respect to the model assumptions, the market share of natalizumab would experience an increase to 8.5%, resulting in a total per-member, per-month healthcare cost increase of $0.003 ($0.002 for pharmacy costs and $0.001 for medical costs).

Regarding CD, over a 2-year period outlined by the model, natalizumab produced the highest average time in remission, steroid-free remission, and remission or response in comparison to the other agents. The mean total costs associated with the initiation of natalizumab, infliximab, and adalimumab were $68,372, $62,090, and $61,796, respectively. Although natalizumab's costs were higher, the mean time spent in remission while on this medication was 4.5 months, as opposed to 2.4 months for infliximab and 2.9 months with adalimumab. This shift in market share was used to estimate the change in total costs (medical + pharmacy), and the per-member per-month change for the model's base case was calculated to be $0.035.

Limitations: The aforementioned cost-effectiveness results for natalizumab in the treatment for CD and MS were limited by the model's predetermined assumptions. These assumptions include anticipated reduction in relapse rate after 2 years of therapy and acquisition costs in the MS model, as well as assuming a certain percentage of patients were primary and secondary failures of TNFα inhibitor therapy in the CD model.

Conclusion: The evidence presented here demonstrates that natalizumab provides clinical practitioners with another tool in their fight against both MS and CD, albeit by way of a different mechanism of action. After a thorough review of the evidence, the authors find that natalizumab has been shown to be relatively cost effective in the treatment of both conditions from a payer perspective; the therapy adds a new option for those patients for whom conventional treatment was unsuccessful.     

Optimal speed of transition with a shrinking labour force and under uncertainty*

In the 1990s – during the restructuring of large state enterprises – Central European economies experienced high unemployment. Social policy expenditures, particularly targeted to the non‐employed, grew faster than expected due to the need to finance the out‐of‐the‐labour categories. In 1992, after the Passive Labour Market Policies’ reforms, the pace of transition decelerated. Unemployment dynamics, speed of transition and non‐employment policies are modelled based on the assumption that the labour force is shrinking over time. Dismissed workers have the opportunity to choose an outside‐option alternative to labour force participation. Individual uncertainty is assumed in a first phase of transition, while aggregate uncertainty – generating opposition to restructuring – is modelled in a second phase. The model predicts a slowdown in the speed of transition.     

Beyond the lamppost: Optimal prevention and control of the Brown Tree Snake in Hawaii

We develop an integrated model for the prevention and control of an invasive species. The generality of the model allows its use for both existing and potential threats to the system of interest. The deterministic nature of arrivals in the model enables clear examination of the tradeoffs inherent when choosing between prevention and control strategies. We illuminate how optimal expenditure paths change in response to various biological and economic parameters for the case of the Brown Tree Snake in Hawaii. Results suggest that it is more advantageous to spend money finding the small population of snakes as they occur than attempting to prevent all future introductions. Like the drunk that looks for his keys only where the light is, public policy may fail to look “beyond the lamppost” for snakes that have already arrived but have not yet been detected. Actively searching for a potential population of snakes rather than waiting for an accidental discovery may save Hawaii tens to hundreds of millions of dollars in future damages, interdiction expenditures, and control costs.     

Strategic foresight in corporate organizations: Handling the effect and response uncertainty of technology and social drivers of change

Today many companies in many industries put a lot of efforts into monitoring and investigating emerging drivers of change in their business environment, particularly in relation to new technologies and events in the social, economic, political and ecological landscapes which surround their industry. So far scholars in the literature on foresight and future studies focused on the techniques and practices for analysing the “state” uncertainty about the likely path of evolution of emerging drivers of change. Anyway, less attention was devoted to the “effect” uncertainty about the impact of drivers of change on the competitive position of the firm and to the “response” uncertainty about how to take advantage of these drivers. These are the main issues we take into account, through a field research on firms that, notwithstanding they were able to properly assess the likely evolution (state uncertainty) of relevant drivers of change in their industry, either were successful or dramatically failed in handling the effect and response uncertainty of these drivers. Moreover, we carried out multiple case studies of some large companies that have established an organizational unit dedicated to strategic foresight. Overall, the results of our research may contribute to improve the effectiveness of strategic foresight and to increase its value added to the planning process of corporate firms, while providing helpful insight to public organizations that promote foresight exercises for enhancing the competitiveness of local firms.     

Evaluating the impact of inequality constraints and parameter uncertainty on optimal portfolio choice

We present new analytical results for the impact of portfolio weight constraints on an investor’s optimal portfolio when parameter uncertainty is taken into account. While it is well known that parameter uncertainty and imposing weight constraints results in reduced certainty equivalent returns, in the general case, there are no analytical results. In a special case, commonly used in the funds management literature, we derive analytical expression for the certainty equivalent loss that does not depend on the risk aversion parameter. We illustrate our theoretical results using hedge fund data, from the perspective of a fund-of-fund manager. Our contribution is to formalize the framework to investigate this problem, as well as providing tractable analytical solutions that can be implemented using either simulated or asset manager returns.     

Cost effectiveness of rosuvastatin in patients at risk of cardiovascular disease based on findings from the JUPITER trial

Abstract

Objective:

This study assessed the long-term cost effectiveness of rosuvastatin therapy compared with placebo in reducing the incidence of major cardiovascular (CVD) events and mortality.

Methods:

A probabilistic Monte Carlo simulation model estimated long-term cost effectiveness of rosuvastatin therapy (20?mg daily) for the prevention of CVD mortality and morbidity. The model included three stages: (1) CVD prevention simulating the 4 years of the JUPITER trial, (2) initial CVD prevention beyond the trial, and (3) subsequent CVD event prevention. A US payer perspective was assessed reflecting direct medical costs, and up to a lifetime horizon. Sensitivity analyses tested the robustness of the model estimates.

Results:

For a hypothetical cohort of 100,000 patients at moderate and high risk of CVD events based on Framingham risk of ≥10%, estimated quality-adjusted life-years (QALYs) gained with rosuvastatin therapy compared with placebo was 33,480 over a lifetime horizon, and 25,380 and 9916 over 20-year and 10-year horizons, respectively. Approximately 12,073 events were avoided over the lifetime; 6,146 non-fatal MIs, 2905 non-fatal strokes, and 4030 CVD deaths avoided. Estimated incremental cost-effectiveness ratio (ICER) for cost per QALY was $7062 (lifetime), $10,743 (20-year horizon), and $44,466 (10-year horizon). For a hypothetical cohort similar to the overall JUPITER population, the cost per QALY ICER was $11,025 for the lifetime and $60,112 for a 10-year horizon.

Limitations:

The cost-effectiveness comparison of rosuvastatin 20?mg was against no active treatment (as opposed to an alternative statin) due to lack of comparative cardiovascular morbidity and mortality risk reduction data for other statins in a population similar to the JUPITER trial population. The analysis was conducted from the payer perspective and lack of inclusion of indirect costs limit interpretability of results from a societal perspective.

Conclusions:

Treatment with rosuvastatin 20?mg daily, is a cost-effective treatment alternative to no treatment in patients at a higher risk (Framingham risk ≥10%) of CVD.     

Individual preferences and the effect of uncertainty on irreversible investment

This paper considers a relationship between investment behavior and an agent’s preferences in a stochastic one-sector growth model with irreversible investment. Further, it explores the effect of uncertainty in investment policies by using a non-expected utility function. Since uncertainty has an impact on investment policies not only through an option value but also through a risk-adjusted time preference rate in a general equilibrium framework, it is significant to distinguish the two preference parameters of the agent. While the previous partial equilibrium models with irreversible investment have exhibited a negative relationship between the desired capital stock and uncertainty, this paper implies that it is possible to generate a positive relationship for the appropriate parameters. This shows that the results of Hartman and Abel have been robust even in a general equilibrium model.     

Model uncertainty and the effect of shall-issue right-to-carry laws on crime

In this paper, we explore the role of model uncertainty in explaining the different findings in the literature regarding the effect of shall-issue right-to-carry concealed weapons laws on crime. In particular, we systematically examine how different modeling assumptions affect the results. We find little support for some widely used assumptions in the literature (e.g., population weights), but find that allowing for the effect of the law to be heterogeneous across both counties and over time is important for explaining the observed patterns of crime. In terms of model uncertainty, we find that there is substantial variation in the estimated effects for each model across all dimensions of the model space. This suggests that one should be cautious in using the results from any particular model to inform policy decisions.     

增值税两类纳税人身份选择的新思考

我国现行税收政策上的差别造成了增值税两类纳税人税收负担上的差别,也为纳税人选择税收身份进行税收筹划提供了可能性。本文对目前国内主流的税收筹划教材、书籍及相关刊物上关于增值税两类纳税人身份选择的税收筹划方案提出了质疑,站在纳税人税后利润最大化的角度对其进行了分析和总结,得出了与前者不同的结论。     

Modelling the clinical and economic implications of galantamine in the treatment of mild-to-moderate Alzheimer's disease in Germany

Abstract

Objective:

This analysis was to assess the long-term clinical and economic implications of galantamine in the treatment of mild-to-moderate Alzheimer's disease (AD) in Germany.

Methods:

An economic model was developed using discrete event simulation to predict the course of AD through changes in cognition, behavioural disturbance, and function over time. It compares the costs and benefits of galantamine versus no-drug treatment and ginkgo biloba. Clinical data were mainly derived from analyses of pooled data from clinical trials. Epidemiological and cost data were obtained from literature and public data sources. Costs (2009 euros) from the perspective of the German Statutory Health Insurance were used.

Results:

The mean survival time for the model population is about 3.44 years over 10 years of simulation. Galantamine delays average time to severe stage of the disease by 3.57 and 3.36 months, compared to no-drug treatment and ginkgo biloba, respectively. Galantamine reduces time spent in an institution by 2.34 and 2.21 months versus no-drug treatment and ginkgo biloba, respectively. The use of galantamine is projected to yield net savings of €3,978 and €3,972 per patient versus no-drug and ginkgo biloba treatments. These results, however, may be limited by lack of long-term comparative efficacy data as well as data on long-term care costs based on multiple outcome measures.

Conclusion:

Compared to no-drug treatment and ginkgo biloba, galantamine therapy provides clinical benefits and achieves savings in healthcare costs associated with care for patients with mild-to-moderate AD in Germany.     

官商结盟的体制效应——以近代中国民营企业发展为例的分析

开放经济条件下,在一个相对集权的体制中,为规避潜在的风险,民营企业通常会采取消极适应或积极适应两种发展形式。以牺牲企业对外部(技术、市场)变化适应性为代价换取产权安全的消极适应型发展的直接后果是使得政府提升国家产业竞争力的努力受挫。与消极适应型发展模式不同,一些民营企业会选择积极适应型的发展模式,即通过寻求官方庇护的政治方式来确保创新收益安全,企业发展与滋生腐败之间极易发生联系。‘腐败’成为企业发展‘润滑剂’现象的出现,侵蚀了国家政治体制,加剧了政府和社会大众的不满,客观上加大了企业发展面临的潜在风险。体制怪圈的形成,既不利于国家竞争力的提升,又极可能引发政府统治的合法性危机。本文分析表明,只有将民营企业从坏体制始作俑者的角色中解放出来,才能破解体制怪圈。这需要从根本上改变民营企业既是被需要的,同时又是被歧视的尴尬处境。中国近代史上有关民营企业发展的案例为本文假说提供了丰富的实质性内容。     

中国通用航空产业补贴效率及最优补贴制度研究—以低空飞行服务业为例

补贴效率是检验补贴制度设计合理性、运行有效性的核心标准。研究发现,我国通用航空飞行服务业补贴制度存在相对供给挤占、暂时性收益陷阱、恶性亏损经营和资金体内循环4类突出的效率损失及福利侵蚀问题,补贴对通航运营企业经营效益提升无显著影响。立足补贴效率受损形式并顺应有效供给和需求严重不足的产业发展矛盾,以社会福利和外部性为核心,从结构重塑、机制优化两个维度出发,全面建立我国通用航空飞行服务业补贴制度并探讨最优补贴边界,最大化补贴效益。首先,以需求二维影响机制为理论支撑,搭建“需求侧保险费率补贴制度+供给端弹性补贴计划”的双侧补贴模式,减缓有效供需规模偏小对企业短期非理性补贴行为的过度激化。其次,从调整补贴标准、丰富补贴层次、规范补贴流程、定位补贴属性4个方面着手深度优化供给侧补贴计划,并以应用事后补贴安排、筹建再保险补贴基金的形式细化需求侧补贴内容,以期最大程度减少补贴效率损耗对预期补贴福利的影响。