Balanced portfolio via signed graphs and spectral clustering in the Brazilian stock market

Quality & Quantity - A portfolio associated with a balanced signed graph that contains both positive and negative edges is more predictable and risk-averse, and is therefore likely to require...     

Mountaineering in Cuba: improvement of true accessibility as an opportunity for regional development of communities outside the tourism enclaves

Mass tourism began in the Caribbean during the middle of the twentieth century. Unfortunately, increasing competition and a change in the motivation of tourists now force the authorities who manage these regions to introduce a new tourism offer that is not based directly on either the 3S (Sun, Sand, and Sea) or 3E (Entertainment, Excitement, Education) model. Hiking, trekking, and climbing, defined as mountaineering, might be one of these. This paper examines the potential for mountaineering in Cuba by verifying its accessibility for tourists. The assessment is based on a framework of true accessibility, which consists of two factors: (1) destination accessibility and (2) real access. Our results show that mountaineering in Cuba should be considered to be one of the key contributors to the development, prosperity, and well-being of all stakeholders, and especially for the communities outside the tourism enclaves.     

通过预防召回获得边际竞争优势

对消费品公司来说，产品召回是一个严重的问题。在美国，每年因为安全原因有成千上万的产品被召回。如图1所示，在1999年和2001年间，14个主要类别的消费品的召回数量在稳定地增加。保守地估计，每个公司召回的平均成本多于800万美元，包括对消费者的赔偿。对消费品行业来说，这可以转化为多于60亿美元的成本，这个估计不包括市场信誉造成的销售损失和失去的市场份额。     

Institutional Environment and Technical Efficiency: A Stochastic Frontier Analysis of Cotton Producers in West Africa

This paper examines the effects of the institutional environment on West African cotton farmers’ technical efficiency (TE). First, key aspects of the cotton sector institutional environment are discussed, including input and credit access, and producers’ organisations. Then, a stochastic frontier production function, which incorporates technical inefficiency effects, is applied to farm level data collected in Benin, Burkina Faso and Mali. The survey includes farmers’ evaluations of the cotton sector institutional environment. Results suggest that institutional level features influence producers’ TE, besides farm‐level characteristics. Cotton growers who report a negative experience with the joint liability programme, who identify the cotton price mechanism or access to credit as the main constraints to performance, and who cultivate more hectares of cereals are technically more inefficient in producing cotton. Findings suggest that cotton farmers in Mali are less technically efficient in producing cotton than in Burkina Faso and Benin. Agricultural development policies focusing on reducing farmers’ financial stress, particularly through the establishment of adequate price mechanisms (i.e. higher farm‐gate prices and timely payments to farmers) and improvement in the input–credit markets should be encouraged to improve TE in West Africa.     

Seasonal labor constraints and intra-household dynamics in the female fields of southern Cameroon

African agricultural production is modeled as a sequential decision process, with men's labor first allotted to clearing, then women's labor allotted to harvesting. A switching regression is then used to measure the constraints due to clearing labor capacity and harvesting labor capacity. The import of men's clearing labor depends on the valuation of shadow wages. Output appears to be more frequently constrained by husband's clearing labor, and in this situation male labor appears under‐utilized. However, output is also significantly constrained by female harvest labor, although the findings imply that female labor is over‐utilized at this stage.     

EBITDA margin in brazilian companies Variance decomposition and hierarchical effects

This study explores the controversy between the business and academic perspectives regarding earnings before interest, taxes, depreciation, and amortization (EBITDA). Some authors argue that EBITDA is not useful as an indicator, except for comparing companies within the same sector (Assaf Neto, 2003, McClure, 2006, Stumpp, 2000). On the other hand, the business world strongly uses this type of indicator as a tool to support its decisions (Schmalensee, 1985, Moraes, 2005). This difference in opinions has aroused interest in understanding the reasons for its use and has raised questions regarding the usefulness of EBITDA for comparing companies from both the same and different sectors. By applying Hierarchical Linear Modeling (HLM), the main goal of this research is to observe EBITDA behavior across companies selling goods in Brazil, comparing them within the same sector and across different sectors over time. This research allows for the analysis of the reasons why EBITDA patterns occasionally occur. The results show significant variation in EBITDA among companies across the same sector and across companies from different sectors. On the other hand, our results have shown, nevertheless, that the variability among companies from the same sector was the highest one, raising questions on the actual usefulness of this indicator to compare companies from the same sector.     

Prices,institutions, and determinants of supply in the Malian cotton sector

Cotton, both a source of livelihood for millions of poor rural households and a major source of export revenues, is a vital commodity for the economic and social development of Mali. Inefficiencies in the Malian cotton system at the ginnery and producers’ cooperative levels (e.g., late payment to farmers and poorly functioning credit schemes) have recently led to an important decline in supply, threatening the sustainability of the sector. Using regional data from 1998/1999 to 2008/2009, this study aims to quantitatively assess the contribution of key determinants, such as cotton prices and timely payment, toward the downward trend in cotton area. A dynamic supply model, based on adaptive expectations and partial adjustment, is employed to estimate the effects of prices and institutional factors, such as credit recovery rates and date of payment to farmers, on the Malian cotton supply. Results show that supply responds significantly to cotton prices relative to cereal and fertilizer prices. Date of payment varies across agricultural cycles and late payment negatively influences land devoted to cotton. Low credit repayment rates create disincentives to grow cotton. Therefore, the revitalization of the Malian cotton sector depends upon getting both prices and institutions right.     

中国的设备投资与经济开放

从传统的Solow增长模型的视角看,资本积累与政府政策对于经济的长期增长都是无效的.但是从内生增长理论的视角看,资本积累(特别是设备投资)和经济开放程度都是长期经济增长最重要的决定因素.长期以来,中国保持高速持续发展的策略主要集中于在市场化进程和贸易开放进程中鼓励投资,以及最近实行的鼓励出口,这一策略允许从更为发达的国家进口研发密集型的机器设备.在这个背景下,本文的目的在于探讨设备投资与出口是否如内生增长理论模型所言对经济增长具有长期的效应,或者相反,如传统的增长模型所言对中国的经济增长没有解释力.除此之外,我们还检验了设备投资、出口和产出在长期和短期的本质联系.在方法上,我们采用了协整VAR模型.我们的发现为设备投资和出口都是导致中国过去数十年中高速发展的重要因素这一观点提供了证据.     

Can the link between functional and personal income distribution enhance the analysis of inequality?

The aim of this paper is to present a framework which links functional and personal income distribution. In the first part of the paper, Piketty’s book “Capital in the XXI Century” is briefly reviewed. Piketty’s framework is discussed arguing that it can only partially explain levels and changes within personal income distribution. Piketty links the returns from capital r to the rate of growth of national income g in a very innovative way comparing them within a macroeconomic framework. He claims that when returns on capital rise more quickly than the overall economy and taxes on capital remain low, a vicious circle of ever-growing dynastic wealth and growing concentration of wealth takes place. However, the rise in the inequality of personal income distribution cannot only be explained by the rise of capital incomes. An analysis of the generation of personal incomes, and consequently of inequality, requires a suitable framework that links incomes at the macroeconomic level (national accounts) and incomes at the level of the individual/household. It is possible to set up this framework starting from individual endowments and their link to the productive structure: that is to what can be called the “generating function of personal income.” This function transforms personal endowments into personal earnings, given the productive structure, the technologies, and the market rules that determine the functional distribution. Personal income distribution and its inequality are linked to the functional one through the shares of capital and labor owned by each individual. The framework introduced here seems to be a suitable tool to account for the fact that personal income distribution is inextricably tied up to different sources of inequality in the distribution of national income. Sources come from institutional and productive structures (matrix Y), but also from the distribution of endowments and of individual/household entitlements (matrix S). This approach, we argue, allows for the assessment and evaluation of the effects of “ambitious new policies,” aimed at reducing poverty and inequality ex-ante, as suggested by Atkinson in his last book.