Stock Size Research Articles

Examining the Q-Factor Model in the Chinese Stock Market

The aim of this paper is to compare model the q-factor model with the Fama-French three-factor using multiple regression techniques and tests. This is done by constructing the market, size, value, investment, and return-on-equity factors with features tailored for the Chinese stock market using 60-month pre-COVID Chinese stock market data. One specific feature tailored for the Chinese stock market, which is eliminating the bottom 30% size of stocks to avoid shell value contamination of returns, is explained. Differences and similarities between the Chinese and the U.S. stock market that can be observed in the process and the results of the regressions and tests are discussed in the paper. It can be concluded that both models behave well in the chosen period of the Chinese stock market, but the q-factor model works slightly better. Other explanatory explorations are done in the paper as well. Limitations of the models due to practical reasons, e.g., the inconsistent changing dynamic of the Chinese stock market institution, and potential further explorations, e.g., potential shell stock pricing strategies, are also discussed in the paper.

Pretty Darn Good Control: When are Approximate Solutions Better than Approximate Models.

Existing methods for optimal control struggle to deal with the complexity commonly encountered in real-world systems, including dimensionality, process error, model bias and data heterogeneity. Instead of tackling these system complexities directly, researchers have typically sought to simplify models to fit optimal control methods. But when is the optimal solution to an approximate, stylized model better than an approximate solution to a more accurate model? While this question has largely gone unanswered owing to the difficulty of finding even approximate solutions for complex models, recent algorithmic and computational advances in deep reinforcement learning (DRL) might finally allow us to address these questions. DRL methods have to date been applied primarily in the context of games or robotic mechanics, which operate under precisely known rules. Here, we demonstrate the ability for DRL algorithms using deep neural networks to successfully approximate solutions (the "policy function" or control rule) in a non-linear three-variable model for a fishery without knowing or ever attempting to infer a model for the process itself. We find that the reinforcement learning agent discovers a policy that outperforms both constant escapement and constant mortality policies-the standard family of policies considered in fishery management. This DRL policy has the shape of a constant escapement policy whose escapement values depend on the stock sizes of other species in the model.

Qualitative Assessment of Status of Fishery Stocks of Black-Spined Herring Alosa kessleri kessleri Alosidae in Volga River Delta with LBI Method

The outcomes of qualitative assessment of the status of fishery stocks of the black-spined herring Alosa kessleri kessleri in the Volga River Delta have been reported. The data on the size composition of catches of the black-spined herring who migrated to the Volga River Delta to spawn in species peak fishing seasons in 1990–2000 and the latest data for 2016–2021, when the low biological values after the period of rapid decline in the stock size in the early 2000s, are used. The length-based indicator method assigned to the methods applied to assess data-poor fish stocks was used to determine indicators for the black-spined herring status in 1990–2000 and 2016–2021. This method allowed us to assess the qualitative status of stocks and the impact of fishery on them in the study periods. The outcomes may be used in recommеndations for black-spined herring fishery regulation.

Влияние ограничения или отказа от табакокурения на адаптационные возможности организма в условиях антарктической зимовки

The research was conducted by a member of the 60th Russian Antarctic Expedition at the all-yearround Mirny Station. The purpose was to study the effect of changed patterns of tobacco smoking on the adaptive capabilities of polar station staff. Materials and methods. Adaptive capabilities were evaluated using the method of cardio-respiratory synchronism, assessing the index of regulatory and adaptive status (IRAS). It is based on recording the synchronization parameters of controlled high respiratory rate and heart rate. IRAS dynamics was compared in four subjects (three regular smokers and one non-smoker as a control) over the course of one year of wintering. The subjects had comparable anthropometric data, health status and working conditions at the station. They were exposed to a similar amount of adverse environmental factors due to their professional activities and lived according to the station’s standard schedule without any personalized changes in their day regimen. Smoking patterns were determined by independent decisions of each expedition member and by the size of personal stocks of tobacco products prepared for the wintering. Results. In polar expedition members faced with smoking cessation or inability to adequately meet this need, IRAS decrease, being a marker of human adaptive capabilities, allowed us to determine the relationship between pronounced changes in the dynamics of regular tobacco smoking and body’s adaptive capabilities. The authors assume that organizational arrangements (sufficient stocks of nicotine-containing products such as cigarettes and tobacco) at the station as well as educational activities (dissuading expedition members from abrupt non-supervised changes in their smoking patterns during Antarctic wintering and properly explaining the reasons why such actions are undesirable) may contribute to improving the health of expedition members and optimizing their living conditions at the polar station. Completing a smoking cessation programme with medical supervision in advance (while preparing for a polar expedition) as well as upon returning from the station (at the end of the adaptation period) can be recommended.

Econometric analysis of profit efficiency of broiler farms in Ondo state, Nigeria

Researchers have recently focused their attention on the chicken producers' inability to produce in sufficient quantities and quality, which contributes to the high price of locally produced chickens. The study investigated the profit efficiency of broiler farms in Ondo state, Nigeria. In order to collect cross-sectional data from sixty owners of broiler poultry farms in the study area between October 2021 and January 2022 for the 2021 production year, a multistage survey technique was used. The data were an-alyzed using descriptive statistics, gross margin and Cobb-Douglas stochastic profit frontier model. Average stock size and mortality rate of farmers were 1826 birds and 3.3% respectively while Ross strain of birds was most preferred birds. The result indicated that broiler farming is a lucrative busi-ness with a profitability index of 45.5 %. The results reveal that the cost of feed, cost of labour used and day-old chicks were the variables that significantly explained the profit efficiency of broiler poul-try farms while household size, years of experience and other income source were the profit inefficien-cy variables. The study recommends government supports to broiler farms in form of input subsidies to enhance efficiency

Pollution control: Assessing the Variable Decay of the Pollution Stock in the Environmental Economics Analysis

Pollution control: Assessing the Variable Decay of the Pollution Stock in the Environmental Economics Analysis

Integrated optimization of rolling stock allocation and train timetables for urban rail transit networks: A benders decomposition approach

We investigate the integrated optimization of rolling stock allocation and train timetables (RATT) in an urban rail transit network with multiple connected lines and rolling stock depots. Different from most existing research on single-line cases, we consider that the rail manager plans to allocate a certain fleet of rolling stock to depots to implement the operational timetables of multiple lines, where each depot can serve more than one line but has limited capacity. By means of the construction of a space–time network, we formulate RATT into a bi-objective mixed-integer linear programming (MILP) model. The model can simultaneously generate the rolling stock allocation plan and train schedules for the considered lines, with the aim of optimizing both the investment cost of rolling stock and the service quality of passengers. Due to the computational complexity of large-scale real-world instances, we develop a Benders decomposition-based solution algorithm, which decomposes the MILP into a rolling stock assignment problem and a set of independent subproblems, i.e., a train scheduling subproblem for each line. As the subproblems also contain integral variables, we further prove that a large portion of the subproblems, after proper reformulation, has the integrality property and can be solved rapidly via linear relaxation. We test our integrated approach and solution algorithms on real-world instances from the Beijing rail transit network. The results show that our solution approach can obtain near optimal solutions, while the commercial solvers cannot even return feasible solutions on real-world instances. Compared to the existing plan in the Beijing metro, our RATT approach can improve the service quality by 17.6%, on average, using the same fleet size of rolling stock.

Learning income levels and inequality from spatial and sociodemographic data in Germany

This study explores the potential of predicting income inequality and income levels from attributes of the built, natural and social environment in Germany. Furthermore, it investigates differences in explanatory variables and estimation accuracy for municipalities with different social and spatial structure profiles. We use income tax data, the 2011 national census, and spatial data from various sources. The explanatory variables capture the spatial variation within the area of interest of characteristics of both the residents and the living environment. Our models explain 54% of the variability in inequality and 73% of the variability in median income levels for a sample of municipalities covering 97% of the country's population. Performance increases for the subsample of municipalities with at least 10,000 inhabitants, attaining 63% for inequality and 80% for income levels. Income inequality and top incomes are better identified in Western, urban, or central locations, while median income is best estimated in Eastern, rural and peripheral locations. The most important predictors are derived from attributes such as nationality, religious affiliation, household composition, residence construction year, as well as the size and density of residences and overall building stock. Our findings further the idea that the joint spatial analysis of population and the built environment can greatly improve our understanding of socioeconomic phenomena—at regional and local levels—beyond conventional data sources.

Fishing and stock assessment of the Siberian Cisco Coregonus sardinella (Coregonidae) in the Gydan basin

This study provides information on the long-term catch and fishing structure of the Sardine cisco Coregonus sardinella in the Gydan basin. A brief biological characteristic of the species is presented. Using the population model CMSY estimates of the size of the Siberian grouse stock and guidelines for managing its fishery were obtained. The model values of biomass turned out to be close to the results of studies in the 1980s.Based on the data obtained, a conclusion is made about the high number of siberian cisco in the basin under consideration. Various forecast scenarios for further management of the fishery are proposed.

Overestimating management progress—modelled vs. monitored silver eel escapement in a North Sea draining river

Abstract The success of European efforts towards the recovery of the European eel (Anguilla anguilla) population will rely on accurate assessments of local stock status for the implementation of conservation measures. Yet, direct and continuous monitoring of the escapement of potential spawners (“silver eels”) is unfeasible in most habitats. Therefore, population models are widely used to estimate local silver eel escapement, but require input information on recruitment, demographic characteristics, and mortalities that are often estimated with great uncertainties. We conducted a combined mark–recapture and acoustic telemetry study across two migration seasons to quantify the actual silver eel escapement in a sub-catchment of the German river Ems. Results were compared with predictions from the demographic model used to provide stock parameters in Germany according to the EU eel-regulation. Mark–recapture results suggested an annual female silver eel escapement of ∼15–17 tons, while the demographic model predicted 90–98 tons, indicating a considerable overestimation. Our results suggest that realistic prediction of silver eel escapement is hardly feasible without high-quality input information and highlight the need for site-specific model calibrations against monitoring data. Overestimations of local stock sizes are problematic if they obscure the necessity for adequate conservation measures, hindering their implementation.

Sustainable stingray stock (Dasyatis sp.) in Malacca Strait, Serdang Bedagai Regency

Sustainable stingray stock catches and increasing the potential that these fish populations may become overfished this may have a negative impact on the size of fish stocks. In order to estimate stock models and prospective resources of stingrays in the seas of the Malacca Strait, the descriptive technique was utilized to collect secondary data. The necessary to conduct stock dynamics research that examines the exploitation rate of stingrays. Based on the Schaefer model, obtained the value of sustainable potential (MSY) for Stingray resources (Dasyatis sp.) at Tanjung Beringin fishing port of 37,24625 tons/year and the optimum effort value of 148,6119 trips/ years. The percentage of stingray resource utilization rate which landed in Tanjung Beringin TPI during the last 5 years has an average value of 0,925% and an effort level of 1,234%. TAC is 29,797 tons/year, shows that fishing can still be increased to get more optimal results. The value of the allowable catch must be below the MSY value which is 80%. The average allowable catch of stingray (Dasyatis sp.) is 80% of the MSY. This means that fishermen’s catches can still be optimized, but must not exceed MSY limit.

Some Economic Aspects of Sugar as a Strategic Commodity in Egypt

The research aims mainly to study Egyptian food security of sugar through studying of several sub-objectives represented in: estimating some economic indicators of sugar in Egypt during the period (2008- 2020), studying of the most important indicators of food security of sugar, estimating the size of the food gap of sugar and knowledge of the most important factors responsible for, and studying the policies and means to achieve food security of sugar in Egypt. Descriptive and quantitative analysis were used. The study depends on secondary data, which collected from local and foreign sources during the period (2008- 2020). The conduct study shows that the most important variables specific to the food gap of sugar are all from the local production of sugar and domestic consumption of sugar where it was found that the impact of each of these two variables on sugar gap be negative. The study showed that the strategic stock of sugar is estimated at 1.15 million tons and the average national consumption of sugar is estimated at 2.17 million tons during the study period (2008-2020) with an annual average during that period , therefore, coefficient of sugar food security estimated at about 0.37, therefore it requires to take various actions that would lead to increase the size of the sugar strategic stock to enough half of it needs for domestic consumption even come close to the value of coefficient of food security, from suitable coefficient of sugar food security. The study showed that the policies and means to achieve sugar food security include horizontal agricultural development policy, vertical agricultural development policy, the policy of rationalizing the consumption of sugar, policy of consumer subsidy of sugar, and the policy of diversifying sources of imported sugar. In the light of the results of the study illustrated by research it has been possible to reach some of the following recommendations: 1- It is necessary to intensify efforts to agricultural extension and agricultural research centers in collaboration with factories engineers and agriculture departments and supervisors agricultural awareness of the importance of agriculture resistance to pests and diseases that affect the crop, and help them get on pesticides is harmful to the environment to do so. 2- Increasing of sugar production through the expansion of sugar crops, particularly sugar beet to the lack of water needs compared to sugar cane harvest in the new land. 3- Increasing of sugar productivity crops through dissemination of sugar varieties of high productivity and to suit every center of administrative centers in Egypt. 4- Rationalizing the consumption of sugar during dismiss the size of the loss of sugar. 5- to achieve food security has to be the need to develop awareness programs for the application of planning policy breeds where it is one of the most important determinants of the demand for i Egyptian imports of sugar. 6- it is important to put a national strategy to increase the self-sufficiency ratio of sugar with the need to import and distribute the amounts of diversification between different sources in order to avoid what might happen from political pressure in favor of the Egyptian economy is in the case of international political conditions change. 7- It is necessary to study the reduction commitments of support granted to the production and export in the sugar-exporting countries in order to reduce the negative effects on the Egyptian Saving.

Determining restoration potential by transplanting mussels of different size classes over a range of aerial exposures

Restoration of mussels typically focuses on either subtidal or intertidal habitats, although it is important to consider the full historical range of a species. However, it remains unclear how environmental changes can impact the ability of mussels to survive in tidal heights where they occurred historically. Additionally, there is limited research on the viability of reducing mussel stock size for restoration purposes. In this study, green-lipped mussels Perna canaliculus of 2 size classes (80 and 60 mm) were assessed when transplanted as a single size class or as mixed cohorts in 9 m2 plots at 3 shore heights (i.e. neap low tide, spring low tide, and subtidal). The mussels were sampled over a 1 yr period to understand the effect that shore height and size class had on mussel metrics, such as survival, growth, and condition. The results revealed that shore height had a greater effect than size class on mussel survival, with a total loss of mussels transplanted into areas that were exposed at neap tides in contrast to 39% mussel survival transplanted into areas that were only exposed on spring low tides. Further, mussels transplanted in the adjacent subtidal had higher overall survival (74%). This suggests that aerial exposure time determines the upper vertical limit for restoration by transplantation of mussels sourced from aquaculture, despite their historical distribution. The results of this study also support the use of smaller mussels (~60 mm) for transplantation for mussel reef restoration, as a 25% reduction in size resulted in 50% more mussels being deployed.

Outward foreign direct investment and urban green productivity: Promote or inhibit?

This paper constructs an empirical model that fits the Chinese context by incorporating human capital, foreign direct investment (FDI), and economic development level into an absorptive capacity category. Concurrently, the model incorporates absorptive capacity into the threshold model. The empirical analysis, using Chinese provincial-level data from 2004 to 2020, shows that outward foreign direct investment (OFDI) activities can promote green total factor productivity (GTFP) and that the green growth effect is more substantial for the stock size of OFDI. Further study finds that OFDI in both regions with lower levels of green growth and lower marketization enhances GTFP; the level of regional marketization also affects the green growth effect of OFDI, with the difference that OFDI negatively affects GTFP when the regional marketization level is higher. The three absorptive capacities of the central variables also affect the green growth effect of OFDI and have a threshold effect on GTFP. OFDI activities thus remain a vital strategy for China's high-quality economic development, and the supportive policies related to OFDI warrant urgent attention. This paper provides empirical evidence and policy implications for fully acknowledging the contribution of OFDI activities in optimizing the absorption capacity channel and improving regional GTFP.

Information Ratio = Selection × Breadth + Sizing

Factor-based performance attribution is an established practice among quantitative and fundamental strategies alike. Although popular, this attribution technique is not of great help to investors interested in understanding the source of their idiosyncratic performance. Of special interest is the ability to separate stock selection skill and sizing skill. Methods aimed at measuring these skills are inspired by analogies to sports. In this article, the author presents an exact decomposition of the information ratio. The IR is the sum of a breadth-adjusted stock selection skill and a sizing skill. The definition of breadth relies on an intuitive measure of concentration—the Herfindahl Index—rather than on the “square root of <italic>n</italic>” measure. These quantities can be compared so that the portfolio manager can determine the percentage of their realized performance originating from each term. In addition, the decomposition empowers the manager to improve their risk-adjusted performance by choosing optimal position sizing, determined by the observed performance of their portfolio. Finally, the decomposition can be further extended to long–short analysis, and provides a natural explanation of an empirical phenomenon: The idiosyncratic performance of the long side of a strategy is often larger than that of the short side.

ANALISIS PENGENDALIAN PERSEDIAAN TEPUNG TERIGU DI UMKM CITRA MENGGUNAKAN METODE ECONOMIC ORDER QUANTITY (EOQ) DAN JUST IN TIME (JIT)

As a Micro, Small and Medium Enterprise that is engaged in the food business, namely crackers, the raw material used in Citra UMKM is wheat flour which is the main raw material in making crackers. raw material. In this study, the authors review controls to determine the size of the safety stock. the availability of raw materials for Citra UMKM by comparing the two availability systems. This study aims to determine the amount of safety stock and when to reorder and compare the availability control system that has been carried out by Citra UMKM using two availability control systems, namely the Economic Order Quantity (EOQ) method and the Just In Time (JIT) method. After further analysis showed that in controlling the inventory of raw materials, the costs incurred by Citra UMKM were greater than those using the Economic Order Quantity (EOQ) method and the Just In Time (JIT) approach. Meanwhile, if the Economic Order Quantity (EOQ) approach is compared with Just In Time (JIT) with each of the total inventory costs between companies, EOQ and JIT are IDR 10,000,000, IDR 1,109,995 and IDR 934,924, using the JIT approach is superior because the number of higher orders and lower total inventory costs.

Ageing of juvenile coral grouper (Plectropomus maculatus) reveals year-round spawning and recruitment: implications for seasonal closures.

Temporal patterns in spawning and juvenile recruitment can have major effects on population size and the demographic structure of coral reef fishes. For harvested species, these patterns are crucial in determining stock size and optimizing management strategies such as seasonal closures. For the commercially important coral grouper (Plectropomus spp.) on the Great Barrier Reef, histological studies indicate peak spawning around the summer new moons. Here we examine the timing of spawning activity for P. maculatus in the southern Great Barrier Reef by deriving age in days for 761 juvenile fish collected between 2007 and 2022, and back-calculating settlement and spawning dates. Age-length relationships were used to estimate spawning and settlement times for a further 1002 juveniles collected over this period. Unexpectedly, our findings indicate year-round spawning activity generates distinct recruitment cohorts that span several weeks to months. Peak spawning varied between years with no clear association with environmental cues, and little to no alignment with existing seasonal fisheries closures around the new moon. Given the variability and uncertainty in peak spawning times, this fishery may benefit from additional and longer seasonal closures, or alternative fisheries management strategies, to maximize the recruitment contribution from periods of greatest reproductive success.

The reproducibility crisis meets stock assessment science: Sources of inadvertent bias in the stock assessment prioritization and review process

The broader scientific community is struggling with a reproducibility crisis brought on by numerous factors, including “p-hacking” or selective reporting that may increase the rate of false positives or generate misleading effect size estimates from meta-analyses. This results when multiple modeling approaches or statistical tests may be brought to bear on the same problem, and there are pressures or rewards for finding “significant” results. Fisheries science is unlikely to be immune to this problem, with numerous opportunities for bias to inadvertently enter into the process through the prioritization of stocks for assessment, decisions about competing model approaches or data treatments within complex assessment models, and decisions about whether to adopt assessments for management after they are reviewed. I present a simple simulation model of a system where many assessments are performed each management cycle for a multi-stock fishery, and show how asymmetric selection of assessments for extra scrutiny or re-assessment within a cycle can turn a process generating unbiased advice on fishing limits into one that is biased high. I show similar results when sequential assessments receive extra scrutiny if they show large proportional decreases in catch limits compared to a prior assessment for the same stock, especially if there are only small changes in true stock size or status over the interval between assessments. The level of bias introduced by a plausible level of asymmetric scrutiny is unlikely to fundamentally undermine scientific advice, but may be sufficient to compromise the nominal “overfishing probabilities” used in a common framework for accommodating uncertainty, and introduce a level of bias comparable to the difference between buffers corresponding to commonly-applied levels of risk tolerance.

TAKING STOCK AND SIZING UP: A STUDY OF THE IMPACT OF IFRS 16 LEASES ON THE STOCK PRICE AND SIZE OF PUBLICLY-TRADED EUROPEAN AIRLINES

ABSTRACT The past few decades for the European airline industry could be described as tumultuous ones. Unforeseeable exogenous shocks such as global contagions, terrorist incidents and fluctuating oil prices have caused increased operational and financial risk for airlines around the globe, including in Europe. Such risks are contrasted against an exigent need for strong solvency and liquidity to fund an array of fixed and variable costs, making the airline model unique in this sense. A further characteristic that typifies this industry is exposure to promulgation of new accounting standards which carry the potential for severe changes to financial reporting. Such a standard, IFRS 16, became effective January 1st, 2019 for publicly-traded firms, mandating capitalization of leased “right-of-use” assets and associated liabilities on airline balance sheets which had previously not been reported. Such a reporting change was significant for airlines with estimates of approximately $3 trillion in newly-capitalized assets. In this study, we analyze a longitudinal dataset spanning 2017-2019 to determine whether passage of IFRS 16 was associated with a statistically significant change in stock price and size, with various proxies employed including market capitalization, total assets and load factors. Other variables including operating income, cash flows from operations, revenues, and debt-to-equity ratio were also examined for any significant changes. The longitudinality of this study was purposively selected to avoid the potentially confounding effects of the Covid-19 pandemic. We show that passage of IFRS 16 was not significantly associated with changes in any of the dependent variables utilized in this research. This study offers valuable findings and a viable contribution to the empirical literature in this field by showing that institutional and individual investors appear to have understood that the extreme changes to the balance sheet were ultimately a reporting nuance rather than a detrimental change to actual cash flows and liquidity. Such findings offer positive implications to financial reporting, costs of capital, market capitalization, and the effect of legislative transparency on airline equities markets. Keywords IFRS 16, Airlines, Leases, Market Capitalization, Load Factor

A mesoplankton biomass decline in the Central Atlantic coupled with an increase of surface temperature and an expansion of low‐productive zones

AbstractAimClimate‐driven trends in environmental processes and their effect on marine ecosystems remain poorly understood despite an obvious decrease in marine biological resources which undergo changes in stock size mediated by phyto‐ and mesoplankton. A mesoplankton multiannual dataset is one of the best tools to elucidate general trends in marine ecosystems.LocationOligo‐ and mesotrophic waters of the Central Atlantic.Time Period1950–2016.Major Taxa StudiedChaetognatha, Cnidaria, Crustacea, Mollusca.MethodsWet mesoplankton biomass (B) values were estimated in 1159 mesoplankton (animals 0.5–30.0 mm long) samples collected in the open ocean epipelagic (0–200 m) in 1950–2016. We ran Generalized Linear Mixed Models and analysed general trends in B, in satellite‐derived surface chlorophyll (Chl, as a proxy of phytoplankton biomass in 1998–2015), and surface temperature (SST, NCEP/NCAR reanalysis, 1948–2015). We further compared the multiannual trends in B, SST, Chl and in space of the oligotrophic and mesotrophic Chl contours in selected regions and in the whole Central Atlantic.ResultsWe showed a statistically significant decline of B within the whole Central Atlantic (9‐fold during 1950–2016) and within each of the three selected regions. These trends were always coupled with other statistically significant effects: increase of SST, decline of Chl, expansion of Chl‐depleted areas and shrinkage of Chl‐enriched areas.Main ConclusionsThe results unveil the following causal relationship in the Central Atlantic: SST increase → strengthening of stratification → Chl decline—expansion of low‐productive areas → B decrease, which, along with existing prognostic climate models, suggests future mesoplankton decline in the Central Tropical Atlantic. The decline in Chl and B is expected to amplify decrease of higher trophic levels biomass and thus to result in changes in the marine food webs. Observed changes in biomass and production will imply direct repercussions for world fisheries and other services provided by Ocean.