A nowcasting model for Ecuador: Implementing a time-varying mean output growth

We propose a model to nowcast the annual growth rate of real GDP for Ecuador, whose economy lacks timely macroeconomic information for some key variables and has gone through unstable periods due to its dependence on oil exports. Our specification combines monthly information for 30 macroeconomic and financial variables with quarterly information for real GDP in a mixed-frequency approach. Our setup includes a time-varying coefficient on the mean annual growth rate of output to allow the model to incorporate prolonged periods of low or high growth. The model produces more accurate nowcasts of real output growth in pseudo out-of-sample exercises than a nowcasting model that assumes a constant mean real GDP growth rate. We also conduct sensitivity analyses on our nowcasting model within the time-varying mean setup and find that including financial variables can be detrimental to the performance of the proposed model.     

The cointegrated vector autoregressive model with general deterministic terms

In the cointegrated vector autoregression (CVAR) literature, deterministic terms have until now been analyzed on a case-by-case, or as-needed basis. We give a comprehensive unified treatment of deterministic terms in the additive model $X_t=\gamma Z_t+Y_t$, where $Z_t$ belongs to a large class of deterministic regressors and $Y_t$ is a zero-mean CVAR. We suggest an extended model that can be estimated by reduced rank regression, and give a condition for when the additive and extended models are asymptotically equivalent, as well as an algorithm for deriving the additive model parameters from the extended model parameters. We derive asymptotic properties of the maximum likelihood estimators and discuss tests for rank and tests on the deterministic terms. In particular, we give conditions under which the estimators are asymptotically (mixed) Gaussian, such that associated tests are ${\chi }^2$-distributed.     

Does e-government performance actually boost citizen use? Evidence from European countries

For many years, it was believed that higher-performing e-government features would boost citizen use of e-services. However, this straightforward proposition had never been tested. Using a survey of over 28,000 citizens across 32 European countries, we examined the effect of e-government performance on citizen use. Theoretically, a better-designed and maintained government website should be used more, but it was reject by multilevel model estimates. We found that performance was negatively related to citizen use of e-information and e-services, while e-participation use was insignificant. The implications of our findings on future efforts to increase the uptake of e-government are also discussed.     

山东省耕地后备资源变化及驱动因素分析

[目的]揭示耕地后备资源变化规律及其驱动因素是进行耕地后备资源合理保护、开发利用的重要基础,但目前对于耕地后备资源变化及驱动因素的研究较为匮乏。[方法]文章以山东省为例,基于2003年和2015年两期耕地后备资源数据库,在分析耕地后备资源时空变化的基础上,采用空间回归模型分析了其变化的驱动因素。[结果]2003~2015年期间,山东省集中连片耕地后备资源减少了30.81万hm~2,其中可开垦土地减少24.97万hm~2,可复垦土地减少5.84万hm~2。[结论]总人口、文盲率、农民人均纯收入、建设用地扩张速度、第一产业产值占总产值比重等是山东省耕地后备资源变化的显著性驱动因素,并且总人口和建设用地扩张的驱动作用最大,受教育程度和产业结构调整的作用次之,农民人均纯收入变化对耕地后备资源变化的影响最小。"宏观统筹协调,异地代补"是解决"耕地后备资源空间分布不均衡、供需不匹配",实现耕地占补平衡、高效合理的开发利用耕地后备资源的必经之路。但异地代补的数量比例和质量应严格控制,并注重对补充耕地地区的经济补偿和政策倾斜,逐步缩小与发达地区之间的差距。     

农民宅基地退出差异性受偿意愿及其影响因素分析

研究目的:宅基地退出工作能否顺利推进与退地补偿息息相关,研究宅基地退出中农民差异性受偿意愿及其影响因素,以服务决策。研究方法:基于重庆市890份农民实地调查数据,应用多元离散选择模型(Logit)进行定量研究。研究结果:(1)传统农区的农民更愿意选择货币补偿;城乡结合部(街道办)的农民更愿意选择安置补偿;农民修建补偿选择率总体偏低,区位差异并不明显;(2)农民货币受偿意愿影响因素主要包括受教育程度、家庭主要成员是否定居城镇、非农务工收入、新居住地适应性;(3)农民安置受偿意愿影响因素主要包括年龄、农房是否自住、退地补偿是否有截留、村基础设施状况;(4)农民修建受偿意愿影响因素主要包括农房造价、农房是否新建、退地补偿是否有截留;(5)影响农民受偿意愿的因素存在较大差异,同一因素可能对农民选择受偿意愿产生不同的影响,但没有一个自变量同时对三个因变量产生显著影响。研究结论:应针对农民受偿意愿差异及其影响因素,实行产异化的补偿措施,在经济发展相对滞后的传统地区,强化村落基础设施建设的同时,加大现金补偿力度。对于经济较为发达、区位条件较好的城乡结合部地区,应加大安置补偿力度,以保障退地农民的居住权。     

The evolution of competition in innovation resource: a theoretical study based on Lotka–Volterra model

This research uses the Lotka–Volterra model to analyse the competition of innovation resource between two enterprises and studies the dynamic effects of environmental changes through the change of model parameters. The research finds that there are three possible results of the competition in innovation resource. That comprises ‘crowding out effect’, ‘unstable equilibrium’ and ‘stable equilibrium’. The results of competitive evolution are determined by enterprises’ interaction parameters. However, the natural growth rates, the initial resource possessions of both enterprises and the amount of regional innovation resource have a significant impact on the evolution of competition.     

Cost analysis of plasma-derived factor VIII/von Willebrand factor versus recombinant factor VIII for treatment of previously untreated patients with severe hemophilia A in the United States

Background: Inhibitor development to factor VIII (FVIII) hemophilia therapy results in increased complications and substantial economic costs. The SIPPET study, the first randomized controlled trial to compare the immunogenicity of plasma-derived FVIII (pdFVIII)/von Willebrand factor (VWF) and recombinant-DNA-derived FVIII (rFVIII), demonstrated higher inhibitor rates in previously untreated patients (PUPs) treated with rFVIII than in PUPs treated with pdFVIII/VWF.

Objective: To quantify the economic impact of treating PUPs with pdFVIII/VWF vs rFVIII.

Methods: An Excel-based clinical and economic model was developed from a US healthcare payer perspective and run over a 5-year period. The analysis utilized a cohort approach to model patient treatment and outcomes over a monthly cycle to quantify differences in costs of FVIII, bypassing agents, and hospitalizations for serious bleeds. Rates of high-titer inhibitor development were obtained from the SIPPET study. Patients developing high-titer inhibitors were treated with immune tolerance induction (ITI). Patients who developed low-titer inhibitors and those who did not develop inhibitors continued their usual FVIII treatment. Patients who were successfully treated with ITI returned to FVIII treatment, while unsuccessfully treated patients received bypassing agents. Total costs per treated patient were estimated and a one-way sensitivity analysis was conducted to quantify the impact of parameter uncertainty on the model outcomes.

Results: Total cumulative costs per patient over 5 years were $834,621 for pdFVIII/VWF patients and $1,237,163 for rFVIII patients, representing a total saving of $402,542 per patient over the 5-year period, for an average annual saving of $80,508 per patient.

Conclusions: Based on data from the SIPPET study, this analysis found that initiating FVIII treatment in severe hemophilia A PUPs with pdFVIII/VWF has the potential to offer substantial cost savings to healthcare payers, amounting to a one-third reduction in costs.     

江苏省生态农业与生态旅游业耦合研究

[目的]目前我国正处于关键的经济转型期,生态农业和生态旅游业作为生态文明建设的重要产业之一,其耦合发展对于存进产业结构优化升级具有重要作用。[方法]通过构建生态农业与生态旅游业指标体系,采用灰色关联法计算江苏省生态农业与生态旅游业的关联度,进一步通过耦合协调度模型分析两者的协调程度。[结果]生态农业系统与生态旅游系统中的旅游经济、旅游资源和旅游价值的关联度分别为0.719,0.673和0.621,大小顺序分别为旅游经济旅游资源旅游价值,而生态旅游系统与生态农业系统中生态系统、经济系统和社会系统的关联度分别为0.687,0.700和0.626,大小顺序分别为经济系统生态系统社会系统,耦合作用均分别为较强、较强和中等。2012~2016年江苏省生态农业和生态旅游业耦合度处于磨合阶段,但一直在增加,同时耦合水平经历了初级协调发展水平到中级协调发展水平的过程。[结论]江苏省生态农业和生态旅游业的耦合发展仍有进步的空间,今后应加强耦合发展机制,推动两大耦合产业走向更深更广的发展领域,促进生态文明建设,同时保证生态产业的可持续健康发展。     

Research collaboration model in academic social networks

ABSTRACT

This paper proposes a hybrid collaboration recommendation method that accounts for research similarities and the previous research cooperation network. Research cooperation is measured by combining the collaboration time and the number of co-authors who already collaborated with at least one scientist. Research similarity is based on authors’ previous publications and academic events they attended. A weighted directed graph is built to discover new collaborators by using direct and indirect connections between scientists. Moreover, a consensus-based system is built to integrate bibliography data from different sources. The experimental results show that our method improves the recommendation performances over other methods.