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Inference on breaks in weak location time series models with quasi-Fisher scores
Full text linkBased on Godambe's theory of estimating functions, we propose a class of cumulative sum (CUSUM) statistics to detect breaks in the dynamics of time series under weak assumptions. First, we assume a parametric form for the conditional mean, but make no specific assumption about the data-generating process (DGP) or even about the other conditional moments. The CUSUM statistics we consider depend on a sequence of weights that influence their asymptotic accuracy.
Data-driven procedures are proposed for the optimal choice of the sequence of weights, in Godambe's sense. We also propose modified versions of the tests that allow to detect breaks in the dynamics even when the conditional mean is misspecified.
Our results are illustrated using Monte Carlo experiments and real financial data
COVID-19 restrictions and workplace mobility: Synthetic control analysis using Google data
Full text linkThe health mandated restrictions during the COVID-19 pandemic induced permanent changes in the economy and society worldwide. Transformation is mainly noticeable in economic sectors where daily tasks permit some degree of telework (e.g. call centers), and those which replaced in-person business (e.g. delivery services). COVID-19 restrictions in Europe implied a 160% increase in working from home (WFH), with a small decrease after mandated restrictions were removed. This paper employs synthetic control methods with Google data to analyze the casual impact of removing these restrictions on the workplace mobility in cities across four European countries (Spain, Italy, France and Sweden). Findings show a significant average fall of 6.3% in workplace mobility post-restriction relaxation. This result highlight associations with key factors such as COVID-19 cases, city population, sex-ratio, stringency index, and residential mobility, pointing towards a potential increase in remote work adoption. These findings underscore the intricate dynamics of workplace measures and their broader implications for evolving remote work trends
Proyección del rendimiento de cultivos de grano basada en los informes semanales de humedad edáfica y estadio fenológico de SAGyP
Full text linkThe paper proposes to use weekly soil moisture and phenological stage data, provided by SAGyP reports, to predict the yield of corn, soybeans (first and second sow), wheat and sunflower. The adjustment of specific models reveals a close relationship between soil moisture and the final yield of the four crops, regardless of the phenological stage of the crop. This apparent irrelevance of the phenological stage contradicts the agronomic literature, which is mainly based on field trials. However, the coefficients of the proposed models, which in turn can be directly interpreted as yield elasticities with respect to moisture, are consistent with the results of other authors. At the end of the paper, the use of the obtained elasticities to predict the national harvest and optimize the management of the climatic risk inherent to agricultural production at a firm level is discussed
Recovering Unobserved Network Links from Aggregated Relational Data: Discussions on Bayesian Latent Surface Modeling and Penalized Regression
Full text linkAccurate network data are essential in fields such as economics, finance, sociology, epidemiology,
and computer science. However, real-world constraints often prevent researchers from collect-
ing a complete adjacency matrix, compelling them to rely on partial or aggregated information.
One widespread example is Aggregated Relational Data (ARD), where respondents or institutions
merely report the number of links they have to nodes possessing certain traits, rather than enu-
merating all neighbors explicitly.
This dissertation provides an in-depth examination of two major frameworks for reconstruct-
ing networks from ARD: the Bayesian latent surface model and frequentist penalized regression ap-
proaches. We supplement the original discussion with additional theoretical considerations on
identifiability, consistency, and potential misreporting mechanisms. We also incorporate robust
estimation techniques and references to privacy-preserving strategies such as differential privacy.
By embedding nodes in a hyperspherical space, the Bayesian method captures geometric distance-
based link formation, while the penalized regression approach casts unknown edges in a high-
dimensional optimization problem, enabling scalability and the incorporation of covariates. Sim-
ulations explore the effects of trait design, measurement error, and sample size. Real-world ap-
plications illustrate the potential for partially observed networks in domains like financial risk,
social recommendation systems, and epidemic contact tracing, complementing the original text
with deeper investigations of large-scale inference challenges.
Our aim is to show that even though ARD may be coarser than full adjacency data, it retains sub-
stantial information about network structures, allowing reasonably accurate inference at scale.
We conclude by discussing how adaptive trait selection, hybrid geometry-penalty methods, and privacy-
aware data sharing can further advance this field. This enhanced treatment underscores the prac-
tical relevance and theoretical rigor of ARD-based network inference
Towards a Pan- African Renaissance
Full text linkThis is the concluding chapter about a new non-aligned development strategy for Africa. As various African countries break away from neocolonial domination by the Global North, a Pan- African Renaissance becomes a possibility. However, it is a complex process. But startin g with the expanded BRICS and various local resistance movements, the outlines of a Pan- African Renaissance can be seen today. Therefore, I argue that Africa can have some agency for pursuing a Pan- African Renaissance
«От каждого – по способности, всем – поровну» в основе теории международной торговли: Попугаи Вашингтонского консенсуса «на страже» экономики страны.
Full text linkThe main models of international economics categorically assert that free trade benefits all countries, including underdeveloped ones. However, these models are based on assumptions that are completely inadequate for the technological era: the equivalence of highly skilled labor, which also utilizes the most advanced technologies, and unskilled labor, which uses primitive tools and produces Stone Age products. This paper once again examines the most fundamental of all models of international trade: Ricardo's theory of comparative advantage. An extremely instructive example of "proof" of the benefits of free trade for all participants is analyzed, based on complete disregard for the difference in highly skilled and low-skilled labor. It is shown that the universal equivalence of unit of labor is a necessary condition for the mutual benefit of free trade in Ricardo's model. If the value of a unit of labor is differentiated by the qualifications of the workforce, then trade liberalization leads to a decrease in the well-being of the country specializing in primitive types of economic activity
Global mineral companies size and corporate governance
Full text linkThis paper analyses the relationship between the size of Global minerals companies and corporate governance. This is achieved by augmenting and comparing the corporate governance ratings of minerals companies in South Africa to that of the minerals companies world wide. The results show a statistically significant autonomous corporate governance as well as a statistically significant difference in corporate governance of the sampled companies' measures of transparency, comprising required disclosure and additional disclosure, based on size. The results, however, show no statistically significant difference in corporate governance between minerals companies in south Africa compared to the minerals companies in other parts of the world as well as no statistically significant difference in corporate governance of the companies measures of market value, market performance and financial performance. The paper, nevertheless, recommends a continued encouragement of good corporate governance to all companies, including those in the minerals industry, given the adverse consequences of the recent corporate scandals
Impact of the Israel-Hamas War on the global economy
Full text linkThis chapter explores the impact of the Israel-Hamas war on the global economy. The war began on the 7th of October 2023. The war received global attention due to the unexpected nature of attacks on both sides. The study assessed several economic indicators using trend analysis and the Pearson correlation analysis from October 2023 to February 2024. The findings show that there was increased volatility in global financial markets, higher energy prices, decline in revenue from tourism and travels, disruption in trade and global supply chains, increase in the cost of insurance, recession risks, high inflation, rising cost for businesses and delay in business decision making. There is also evidence of spill-over of inflation and GDP shocks to other countries during the war
Grain for Green: Balancing Ecological Protection and Food Security under Climate Change
Full text linkLand use policy is crucial for food security and ecological protection. This study explores the impact of the world’s largest Grain for Green Program, which subsidizes more than 100 million farmers to convert sloped cropland to forests and grasslands, on crop productivity in China. By combining
detailed county-level crop production data with remote sensing data, our difference-in-differences estimates suggest that while the program significantly reduced total cropland area, it led to an increase in total crop yield. The unexpected yield impact can be explained by the fact that the program significantly increased labor input and multiple cropping in the remaining cropland. More importantly, we find that the program substantially reduced the damage of drought and extreme heat on crop yield. Our findings suggest the possibility of adopting land use policy to protect the ecology without compromising food security in a developing country
International monetary policy spillovers between Japan and the Rest of the World: A GVAR Framework
Full text linkWe evaluate the impact of international monetary policy spillovers from the US and China on the real exchange rate of Japan. While China remains the top largest trading partner to Japan, the US occupies the second position, indicating potential policy spillovers from these countries to Japan. Adopting the GVAR modelling technique, the outcomes from our findings suggest: (i) the US monetary policy shocks significantly affect Japanese foreign exchange dynamics, causing Yen to depreciate in the instance of a positive shock to US monetary policy; (ii) monetary policy shocks from China and the Euro Area do not constitute a considerable swing in Yen’s exchange rate; (iii) the US monetary policy shock is insignificant in influencing monetary policy conduct of Japan, at least in the short term; (iv) these findings are robust to calm and turbulent periods. Thus, we offer the implications of our findings for policymakers and investors seeking stability as a macroeconomic goal and a stable economy for investment