A note on estimation based on record data

In data-processing standpoint, an efficient algorithm for identifying the minimum value among a set of measurements are record statistics. From a sequence of n independent identically distributed continuous random variables only about log(n) records are expected, so we expect to have little data, hence any prior information is welcome (Houchens, Record value theory and inference, Ph.D. thesis, University of California, Riverside, 1984). In this paper, non-Bayesian and Bayesian estimates are derived for the two parameters of the Exponential distribution based on record statistics with respect to the squared error and Linear-Exponential loss functions and then compared with together. The admissibility of some estimators is discussed.     

Impact of traffic citations to reduce truck crashes on challenging roadway geometry

Wyoming's Interstate 80 has one of the highest truck crash rates in the United States. This is due to a variety of reasons, including high percentage of truck traffic, adverse weather conditions and mountainous terrain. These factors have caused the Wyoming Highway Patrol (WHP) to spend extensive resources on inspecting commercial vehicles and enforcement of traffic laws in this corridor. This study estimated the correlation between traffic citations and truck crashes. In addition, the paper evaluated the increased risk of truck crashes in adverse weather and road conditions. The explanatory variables included geometric features, weather condition, traffic volume and types of citations. This research concluded that speeding related citations and truck crashes are negatively correlated, and the risk of truck crashes is significantly higher when weather is not clear, and the road is not dry.     

Economic evaluation for the US of nab-paclitaxel plus gemcitabine versus FOLFIRINOX versus gemcitabine in the treatment of metastatic pancreas cancer

Background: Nab-paclitaxel plus gemcitabine (NAB-P?+?GEM) and FOLFIRINOX have shown superior efficacy over gemcitabine (GEM) in the treatment of metastatic pancreatic ductal adenocarcinoma (mPDA). Although the incremental clinical benefits are modest, both treatments represent significant advances in the treatment of a high-mortality cancer. In this independent economic evaluation for the US, the aim was to estimate the comparative cost-utility and cost-effectiveness of these three regimens from the payer perspective.

Methods: In the absence of a direct treatment comparison in a single clinical trial, the Bucher indirect comparison method was used to estimate the comparative efficacy of each regimen. A Markov model evaluated life years (LY) and quality-adjusted life years (QALY) gained with NAB-P?+?GEM and FOLFIRINOX over GEM, expressed as incremental cost-effectiveness (ICER) and cost-utility ratios (ICUR). All costs and outcomes were discounted at 3%/year. The impact of parameter uncertainty on the model was assessed by probabilistic sensitivity analyses.

Results: NAB-P?+?GEM was associated with differentials of +0.180 LY and +0.127 QALY gained over GEM at an incremental total cost of $25,965; yielding an ICER of $144,096/LY and ICUR of $204,369/QALY gained. FOLFIRINOX was associated with differentials of +0.368 LY and +0.249 QALY gained over GEM at an incremental total cost of $93,045; yielding an ICER of $253,162/LY and ICUR of $372,813/QALY gained. In indirect comparison, the overall survival hazard ratio (OS HR) for NAB-P?+?GEM vs FOLFIRINOX was 0.79 (95%CI?=?0.59–1.05), indicating no superiority in OS of either regimen. FOLFIRINOX had an ICER of $358,067/LY and an ICUR of $547,480/QALY gained over NAB-P?+?GEM. Tornado diagrams identified variation in the OS HR, but no other parameters, to impact the NAB-P?+?GEM and FOLFIRINOX ICURs.

Conclusions: In the absence of a statistically significant difference in OS between NAB-P?+?GEM and FOLFIRINOX, this US analysis indicates that the greater economic benefit in terms of cost-savings and incremental cost-effectiveness and cost-utility ratios favors NAB-P?+?GEM over FOLFIRINOX.     

Fuzzy Development of Multiple Response Optimization

This paper proposes a developed approach to Multiple Response Optimization (MRO) in two categories; responses without replicates and with some replicates based on fuzzy concepts. At first, the problem without any replicate in responses is investigated, and a fuzzy Decision Support System (DSS) is proposed based on Fuzzy Inference System (FIS) for MRO. The proposed methodology provides a fuzzy approach considering uncertainty in decision making environment. After calculating desirability of each response, total desirability of each experiment is measured by using values of each response desirability, applying membership function and fuzzy rules expressed by experts. Then Response Surface Methodology (RSM) is applied to fit a regression model between total desirability and controllable factors and optimize them. Next, a methodology is proposed for MRO with some replicates in responses which optimizes mean and variance simultaneously by applying fuzzy concepts. After introducing Deviation function based on robustness concept and using desirability function, a two objective problem is constituted. At last, a fuzzy programming is expressed to solve the problem applying degree of satisfaction from each objective. Then the problem is converted to a single objective model with the goals of increasing desirability and robustness simultaneously. The obtained optimum factor levels are fuzzy numbers so that a bigger satisfactory region could be provided. Finally, two numerical examples are expressed to illustrate the proposed methodologies for multiple responses without replicates and with some replicates.     

Investor Response to Cash Flow Information

In this study the usefulness of cash flow data as required by the UK standard, FRS1 , is evaluated and cash flow per share is investigated as a possible specification of cash flow data that may contain information value for security markets. Recent innovation in earnings response models are used to test the robustness of the results and provide further insights into the time series properties of cash flow numbers. The findings indicate that the disaggregation of cash flow as required under FRS1 contains information beyond aggregate cash flow but that the required disaggregation is not optimal from an information standpoint. There is little evidence of any incremental information value of cash flow per share over cash flow numbers.     

Reclaiming the future : Futures studies in Africa

This article considers the status of futures studies and research in Africa. Compared to the position two decades ago, African planning services today represent a real achievement, and can act as the basis for advanced public policy analysis. Futures studies in Africa can act to stimulate and extend the national planning function, and also provide a unified approach at the regional and continental levels. Futures studies can never be value-free—Africans embarking on futures studies must first rediscover their past and assert their present before they are able to ‘reclaim their future’.     

Collusion Under Risk Aversion and Fixed Costs

We analyze collusion under demand uncertainty by risk‐averse cartels that care about the utility derived from profits. With sufficient risk aversion and non‐trivial fixed operating costs, it becomes difficult for cartels to collusively restrict output both when demand is low and marginal dollars are highly valued, and when demand is high and potential defection profits are high: output relative to monopoly levels becomes a U‐shaped function of demand. Greater risk aversion or higher fixed operating costs make collusion more difficult to support in recessions, but easier to support in booms.     

Determinants of specific trade concerns raised on technical barriers to trade EU versus non-EU

This contribution evaluates determining factors of Specific Trade Concerns (STCs) raised on Technical Barriers to Trade (TBT) notifications over the period 1995–2011. While multilateral and international agreements bind countries concerning the imposition of tariffs on imports, TBTs have been used as trade policy instruments, which conceal the true motivations of governments. The main legitimate reasons behind the imposition of TBTs are to increase environmental qualities and human health, or to improve market efficiencies. However, in addition to these reasons, governments are also in pursuit of protecting their domestic industries. In fact, this contribution analyses how trade protectionist motives and legitimate public policy objectives induce these specific trade measures. Various effective factors of TBT STC notifications are considered in the econometric analysis using fixed effect Poisson estimation as the main technique, and Poisson GMM as robustness specification. Separate estimations on the European Union block in this study points at the determining factors of TBTs harmonized by heterogeneous member states. Results suggest that bilateral trade and tariffs are one of the forces of TBT STC notifications, acknowledging the protectionist behaviour of authorities. Moreover, countries with high quality of humans’ health-related environmental issues, and low environmental vitalities, are more likely to impose new TBTs. Overall, this study confirms the complex nature of TBT STCs affected by economic, technological, institutional, and health and environmental issues.