A note on the projection properties of Hadamard matrices obtained by the first Payley construction

We show that the projections on four factors of an arbitrary orthogonal array of strength 2 allow the estimation of main effects and two-factor interactions when all other effects are assumed to be zero, if those projections satisfy the bounds given by Weils theorem. The only exceptions are the Hadamard matrices of orders 16 and 24. A consequence is again the estimability of main effects and two-factor interactions for the projections on four factors of the first Payley construction for arbitrary run size.     

Using dead reckoning in economic projections

Economics is an inexact science, measurement of basic data is at best approximate, and most interesting relationships change relatively rapidly in developing countries. Key variables determining economic prospects are often impossible to include into models. Models and their mathematical algorithms however are deceptively precise, which often complicates the process of constructing and using economic projection models in developing countries.This paper will examine those macro models intended for operational policy purposes and how they are used. These models try to be analytically good and have sufficient plausibility to influence policy. Thus, a great deal of judgment is required in constructing, using, and interpreting projection models in developing countries: the “dead reckoning” element.     

中国养活自己能力的长期预测:技术和政策分析

中国拥有世界五分之一强的人口 ,收入又在迅速增长。因此 ,国际上很自然地会考虑或推测她在今后的几十年是否有能力养活自己。中国的人口预计将从 2 0 0 0年的 1 2 8亿增长到 2 0 2 0年的 1 4 6亿 ,和 2 0 3 0年的 1 4 9亿。与此同时 ,人均收入的增长将导致对家畜和鱼类产品更大的需求 ,因而对饲料的需求也将有很大的增长     

Forecast reconciliation: A geometric view with new insights on bias correction

A geometric interpretation is developed for so-called reconciliation methodologies used to forecast time series that adhere to known linear constraints. In particular, a general framework is established that nests many existing popular reconciliation methods within the class of projections. This interpretation facilitates the derivation of novel theoretical results. First, reconciliation via projection is guaranteed to improve forecast accuracy with respect to a class of loss functions based on a generalised distance metric. Second, the Minimum Trace (MinT) method minimises expected loss for this same class of loss functions. Third, the geometric interpretation provides a new proof that forecast reconciliation using projections results in unbiased forecasts, provided that the initial base forecasts are also unbiased. Approaches for dealing with biased base forecasts are proposed. An extensive empirical study of Australian tourism flows demonstrates the theoretical results of the paper and shows that bias correction prior to reconciliation outperforms alternatives that only bias-correct or only reconcile forecasts.     

Projections of maize yield vulnerability to droughts and adaptation options in Uganda

Sub-Saharan Africa is likely going to experience more intense and frequent droughts with high parallel possibilities of ramifications on maize yields. While there is a lot of scholarship dwelling on the ramifications of droughts on maize yields at the level of Africa, little has been researched at lower scales. This study presents past (1960–2014) vulnerability of maize yields to droughts based on a previous study (Epule et al., 2017) and projects the future vulnerability of maize yields to droughts by calculating the sensitivity, exposure and adaptive capacity of maize yields to droughts for the period 2015–2050. The results show that maize yields are more vulnerable in the north of Uganda for the period 1960–2014. However, adaptive capacity is higher in the south. Maize yields also record higher levels of sensitivity and exposure in the north with the latter patterns explained by variations in precipitation, temperature, rich volcanic soils, access to rivers and lakes. In terms of future vulnerability for the period 2015–2050, this study shows that the level of vulnerability of maize yields to droughts in Uganda will increase to levels higher than what currently obtains. For example, the vulnerability index will increase from 0.54 under the 1.5 °C to 0.70 under the 2.0 °C and to 1.54 under the 2.5 °C scenario. Sensitivity is also likely to increase while exposure and adaptive capacity are most likely to remain the same. Overall, it can be said that the future of maize production in Uganda under present and future circumstances remains very bleak without concrete actions. As a way forward, land use policy designers will have to integrate water management, agroforestry, climatic information diffusion, training and indigenous knowledge into land use planning decisions in the context of agriculture.     

Probabilistic Population Projections for India with Explicit Consideration of the Education-Fertility Link

Among the different sources of uncertainty in population forecasting, uncertain changes in the structure of heterogeneous populations have received little attention so far, although they can have significant impacts. Here we focus on the effect of changes in the educational composition of the population on the overall fertility of the population in the presence of strong fertility differentials by education. With data from India we show that alternative paths of future female enrolment in education result in significantly different total fertility rates (TFR) for the country over the coming decades, even assuming identical fertility trends within each education group. These results from multi-state population projections by education are then translated into a fully probabilistic population projection for India in which the results of alternative education scenarios are assumed to expand the uncertainty range of the future TFR in the total population.
This first attempt to endogenize structural change with respect to education—which is the greatest measurable source of fertility heterogeneity in Asia—has resulted from a larger exercise of the Asian MetaCentre for Population and Sustainable Development Analysis to collect empirical information, scientific arguments as well as informed opinions about likely future population trends in Asia from a large number of population experts in the region. In this process, future changes in the educational composition of the population have been identified as a key driver of future fertility.
The actual probabilistic population projections for India show that with high certainty, the Indian population will continue to grow to about 1.3 billion over the next quarter of a century. After that the uncertainty will get much wider, ranging from a continued strong increase to the beginning of a population decline in India.     

中国老年人口受教育程度发展趋势前瞻

针对中国教育事业的发展如何影响未来30年老年人口的受教育结构、2050年中国建成现代化强国时老年人口的平均受教育年限是多少等问题进行分析,在运用人口普查以及1%人口抽样调查等数据对中国老年人口教育水平历史演进做出回顾的基础上着重预测未来趋势。结果显示:老年人口在改革开放以来实现了从八成不识字到八成受教育的历史性转变,且男女两性老年人口在受教育程度上的差距趋于缩小;到本世纪中叶,老年人口的平均受教育年限预计可达10年,基本具备高中教育水平,且男女两性老年人口教育不平等的状况将会显著改变,受过高等教育比例快速上升。中国老年人口规模大增长的时代同时也是老年教育水平大提升的时代,这可以为健康老龄化和积极老龄化等创造更有利的发展环境。