中国柑橘主产区的区域比较优势及其影响因素研究*——基于省级面板数据的实证分析

[目的]通过研究我国柑橘主产区的区域比较优势及其影响因素,为我国柑橘产业的发展提供科学依据。[方法]利用2005—2015年全国柑橘产业的相关数据,采用综合比较优势指数模型和资源禀赋系数模型,定量测算了2005—2015年我国柑橘主产区的区域比较优势指数及资源禀赋系数,结合动静态面板数据模型实证分析了柑橘主产区区域比较优势的影响因素。[结果](1)我国柑橘各主产区比较优势明显但差异较大,柑橘产业有从东南沿海地区向中西部转移的强劲趋势;(2)我国柑橘生产的资源禀赋优势较为集中且在不断的发生变化,福建、浙江、四川及湖南4省处于下降趋势,其他主产区均有所上升;(3)资源禀赋、资本投入对柑橘区域比较优势有正向的影响,技术创新的正向影响在动态中显现,经济水平对区域比较优势有负向影响。[结论](1)我国柑橘主产区的区域比较优势受到资源禀赋、资本投入、技术创新、经济水平等因素的综合影响;(2)要根据各主产区的现状条件进一步优化柑橘产业区域布局,提高科技含量,并且要结合当地的经济发展情况以及资源禀赋条件使柑橘产业能够在主产区脱贫和乡村振兴中发挥更大作用;(3)南方沿海地区柑橘产业近年受黄农病影响严重,柑橘产业向中西部转移。     

基于耦合共生理论的田园综合体规划模式建构

[目的]随着城乡统筹发展,乡村振兴战略的实施已成为解决"三农"问题的关键。2017年中央一号文件在乡村的大背景下,首次提出了"田园综合体"的概念,旨在通过实现农业与其他产业的共生融合,来带动乡村的发展及振兴、农业的转型升级、农民生活质量的提高。通过构建多产业耦合共生的田园综合体规划模式,以期更好地实现农业转型升级以及乡村的发展振兴。[方法]引入物理学中的耦合理论以及生物学中的共生理论进行研究。[结果]从耦合共生单元、耦合共生环境、耦合共生界面三个方面提出集农旅合一、多产业联合、多方参与为一体的田园综合体模式规划理念框架。[结论]以农旅合一的耦合共生单元为基础,将文化作为农业与旅游耦合共生的介质,有助于实现文化内涵的提升以及农业与旅游的协同发展;以多产业联动的耦合共生环境为推手进行合理布局,使多产业联动发展,有助于实现资源的整合利用、农业产业附加值的增加、村落结构的完善、农村特色及文化的传承;以多方共同参与的耦合共生介质为保障,通过政府、市场和公众这三方的共同参与和合作,有助于解决三农问题,带动农村经济的发展,促进乡村统筹发展及乡村振兴战略的实施。     

土地整治对中国粮食产出稳定性的贡献

研究目的:研究土地整治对粮食产出稳定性的贡献,为制定合理高效的土地整治政策,促进粮食增产稳产提供依据。研究方法:采用H-P滤波法实证分析中国粮食产量的波动性及增长趋势,然后基于C-D生产函数,分别建立趋势产量和波动强度面板回归模型,分析土地整治对粮食产出稳定性的影响。研究结果:(1)粮食作物播种面积、农业机械总动力、农用化肥施用量均对粮食长期趋势产生不同程度促进作用;农业劳动力对主产区粮食长期趋势影响显著为负,对非主产区却有正向影响。(2)土地整治面积和单位面积投资额均降低了全国及主产区粮食产量的波动程度,土地整治规模在全国和主产区的影响系数分别为-1.4162和-2.2215;单位土地整治面积投资额在全国和主产区的影响系数分别为-0.7589和-1.3509。(3)土地整治新增耕地面积对全国和主产区的粮食产量波动强度影响为正,影响系数分别为0.8018和1.3931。可能是通过土地整治新增的耕地质量较低,产出不高,导致了粮食产量波动。土地整治投入在非主产区均表现为不显著。研究结论:应继续推进尤其是主产区的土地整治项目实施,加大土地整治投资强度,建立长期稳定的投入机制,合理使用整治资金,注重提高新增耕地质量和综合生产能力,同时将土地整治投入和管理机制与农业生产系统运行机制、自然因素等有效结合,并制定差别化区域政策,以保障粮食增产稳产和区域协调发展。     

Drivers and barriers to cross-border e-commerce: Evidence from Spanish individual behavior

This paper explores the determinants of the individual's decision to perform cross-border e-commerce (CBeC). The European Union (EU) is especially interested in the promotion of CBeC because it is an important tool in its strategy to achieve the Digital Single Market in Europe. In this paper official data is used from a representative survey of 16,209 individuals on ICT usage by households and individuals that was carried out in Spain by the National Institute of Statistics (INE) for the year 2016. Using a standard neoclassical utility maximization framework, and logistic regression techniques, the results show that being a male is positively related to the probability of practicing CBeC. Education is positively and significantly related to the probability of being involved in CBeC with EU countries. Computer and Internet Skills are significant and positive factors in explaining CBeC (either with EU countries or with the rest of the world). The variable “how often the consumer sees other customer reviews before buying online”, has a positive effect. Foreign nationality also increases the likelihood of using CBeC. To promote CBeC in Spain measures towards developing digital skills, Internet trust and use of online information reviews of goods and services are discussed.     

A hybrid information approach to predict corporate credit risk

This study proposes a hybrid information approach to predict corporate credit risk. In contrast to the previous literature that debates which credit risk model is the best, we pool information from a diverse set of structural and reduced‐form models to produce a model combination based on credit risk prediction. Compared with each single model, the pooled strategies yield consistently lower average risk prediction errors over time. We also find that while the reduced‐form models contribute more in the pooled strategies for speculative‐grade names and longer maturities, the structural models have higher weights for shorter maturities and investment grade names.     

Data-based mechanistic modelling and forecasting globally averaged surface temperature

The main objective of this paper it to model the dynamic relationship between global averaged measures of Total Radiative Forcing (RTF) and surface temperature, measured by the Global Temperature Anomaly (GTA), and then use this model to forecast the GTA. The analysis utilizes the Data-Based Mechanistic (DBM) approach to the modelling and forecasting where, in this application, the unobserved component model includes a novel hybrid Box-Jenkins stochastic model in which the relationship between RTF and GTA is based on a continuous time transfer function (differential equation) model. This model then provides the basis for short term, inter-annual to decadal, forecasting of the GTA, using a transfer function form of the Kalman Filter, which produces a good prediction of the ‘pause’ or ‘levelling’ in the temperature rise over the period 2000 to 2011. This derives in part from the effects of a quasi-periodic component that is modelled and forecast by a Dynamic Harmonic Regression (DHR) relationship and is shown to be correlated with the Atlantic Multidecadal Oscillation (AMO) index.     

我国农村产业融合发展的效率评价

[目的]为了进一步提升农村产业融合发展效率,提升农业质量效益和竞争力、增强农村发展活力、促进农民持续增收,[方法]文章根据我国农村产业融合发展的投入产出指标数据,利用DEA方法对我国31个省(自治区、直辖市)农村产业融合效率进行了科学的分析与测算,[结果]研究表明,我国农村产业融发展的总体效率偏低。从综合效率看,仅有天津等7个省(自治区、直辖市)的综合效率值高于0. 5;从纯技术效率看,仅有江苏等8个省(自治区、直辖市)的纯技术效率高于0. 5;从规模效率看,西藏、甘肃、青海3个省(自治区)的规模效率低于0. 5。提升农村产业融合发展效率仍有较大的空间。[结论]应从进一步加大对农村产业融合发展的资金投入力度、着力优化农村产业融合发展的资金投入结构、建立农村产业融合发展效率考评制度等方面提升农村产业融合发展效率,促进农村产业融合快速发展。     

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.