scholarly journals A Two-Stage Polynomial and Nonlinear Growth Approach for Modeling the COVID-19 Outbreak in Mexico

Author(s):  
Rafael Perez Abreu ◽  
Samantha Estrada ◽  
Héctor de-la-Torre-Gutiérrez

Since December 2019, the coronavirus disease (COVID-19) has rapidly spread worldwide. The Mexican government has implemented public safety measures to minimize the spread of the virus. In this paper, the authors use statistical models in two stages to estimate the total number of coronavirus (COVID-19) cases per day at the state and national level in Mexico. Two types of models are proposed: first, a polynomial model of the growth for the first part of the outbreak until the inflection point of the pandemic curve and then a second nonlinear growth model is used to estimate the middle and the end of the outbreak. Model selection will be performed using Vuong’s test. The proposed models show overall fit similar to predictive models (e.g. time series, and machine learning); however, the interpretation of parameters is less complex for decision-makers and the residuals follow the expected distribution when fitting the models without autocorrelation being an issue.

Mathematics ◽  
2021 ◽  
Vol 9 (18) ◽  
pp. 2180
Author(s):  
Rafael Pérez Abreu C. ◽  
Samantha Estrada ◽  
Héctor de-la-Torre-Gutiérrez

Since December 2019, the novel coronavirus (SARS-CoV-2) and its associated illness COVID-19 have rapidly spread worldwide. The Mexican government has implemented public safety measures to minimize the spread of the virus. In this paper, we used statistical models in two stages to estimate the total number of coronavirus (COVID-19) cases per day at the state and national levels in Mexico. In this paper, we propose two types of models. First, a polynomial model of the growth for the first part of the outbreak until the inflection point of the pandemic curve and then a second nonlinear growth model used to estimate the middle and the end of the outbreak. Model selection was performed using Vuong’s test. The proposed models showed overall fit similar to predictive models (e.g., time series and machine learning); however, the interpretation of parameters is simpler for decisionmakers, and the residuals follow the expected distribution when fitting the models without autocorrelation being an issue.


2017 ◽  
Vol 13 (34) ◽  
pp. 434
Author(s):  
Giuseppe Granata

Aim: The aim of this paper is to analyze the strategic validity of Italian network contract in order to define a new business model for contemporary enterprises. Methodology: The research method is deductive-inductive with a multimethod approach. The sources are collected through semi-structured interviews and open sources, scientific books and papers, and sectorial database. Findings: The present research is the first step taken in conducting an extended study on a territorial, regional, and national level. Limitations: Research limitations are based on the restricted data used in the present phase of the work. Implications: The paper aim at integrating existing literature for academic community and decision makers. Originality: The research represents essential characteristics of Italian network contract, by emphasizing its framework and validity, in order to recognize an innovative business model in increasing the enterprises competition in the market.


1997 ◽  
Vol 2 (1) ◽  
pp. 123-146 ◽  
Author(s):  

AbstractThe Zapatista rebels of southern Mexico have achieved considerable success both in maintaining themselves against unlikely odds and in coming to agreement with the Mexican government on issues affecting indigenous rights and identity. At the same time, a central demand, both of the Zapatistas and the indigenous movement which they have helped to revitalize, namely revision of the 1992 constitutional reforms affecting corporate claims to land and the possibility of further land reform, has been roundly rejected by the government. The paper explains both Zapatista achievements and the limits to ethnic bargaining evident in the negotiations to date through an analysis of the dynamic process by which both sides came to the negotiating table and shaped and reshaped the rules of the bargaining game. It draws on social movement theory to show how the Zapatistas in particular were able to overcome the ``asymmetry of internal conflict'' and frame the issues, enlarging its base of support to a national level. At the same time, specifically indigenous issues could be resolved much more readily than the larger concerns, including those surrounding landholding, which motivated the rebellion. The shifting political context had much to do with the government's willingness to negotiate; but the Zapatista's skill at assembling a national constituency, attracting international attention, and framing the issues were decisive in achieving accords on indigenous rights. Nevertheless, in the absence of a ``mutually hurting stalemate,'' government negotiators could continue to reject Zapatista demands on issues reaching beyond strictly ethnic concerns.


2020 ◽  
Vol 40 (5) ◽  
pp. 606-618
Author(s):  
Fan Yang ◽  
Colin Angus ◽  
Ana Duarte ◽  
Duncan Gillespie ◽  
Simon Walker ◽  
...  

Public health decision makers value interventions for their effects on overall health and health inequality. Distributional cost-effectiveness analysis (DCEA) incorporates health inequality concerns into economic evaluation by accounting for how parameters, such as effectiveness, differ across population groups. A good understanding of how and when accounting for socioeconomic differences between groups affects the assessment of intervention impacts on overall health and health inequality could inform decision makers where DCEA would add most value. We interrogated 2 DCEA models of smoking and alcohol policies using first national level and then local authority level information on various socioeconomic differences in health and intervention use. Through a series of scenario analyses, we explored the impact of altering these differences on the DCEA results. When all available evidence on socioeconomic differences was incorporated, provision of a smoking cessation service was estimated to increase overall health and increase health inequality, while the screening and brief intervention for alcohol misuse was estimated to increase overall health and reduce inequality. Ignoring all or some socioeconomic differences resulted in minimal change to the estimated impact on overall health in both models; however, there were larger effects on the estimated impact on health inequality. Across the models, there were no clear patterns in how the extent and direction of socioeconomic differences in the inputs translated into the estimated impact on health inequality. Modifying use or coverage of either intervention so that each population group matched the highest level improved the impacts to a greater degree than modifying intervention effectiveness. When local level socioeconomic differences were considered, the magnitude of the impacts was altered; in some cases, the direction of impact on inequality was also altered.


2010 ◽  
Vol 43 (04) ◽  
pp. 639-641 ◽  
Author(s):  
Alfred G. Cuzán

Historically, statistical models for forecasting the outcome of midterm elections to the United States House of Representatives have not been particularly successful (Jones and Cuzán 2006). However, in what may have been a breakthrough, most models correctly predicted that the Democrats would re-emerge as the majority party in 2006 (Cuzán 2007). One successful model was estimated using 46 elections, beginning with 1914 (only the second time that 435 representatives, the present number, were elected). The model was relatively simple, making use of national-level variables only (Cuzán and Bundrick 2006). Using a similar model, I generated a forecast for the 2010 midterm election.


2018 ◽  
pp. 004908571878468
Author(s):  
Imad El-Anis

Since the late 1980s governments in the Middle East and North Africa (MENA) have created commercial institutions in order to promote regional economic integration. The primary aim of this policy has been regarded as the promotion of economic welfare gains at the national level. The second, albeit less-emphasized goal, has been to promote regional peace through economic interdependence. This study examines the prospects for a liberal peace in the MENA by analyzing two stages of the commercial institutional peace. First, the study considers whether commercial institutions have promoted intra-regional trade in the MENA. Second, it examines whether economic interaction has had an impact on promoting peace within the region. Twenty states are considered here and the unit of analysis is the dyad-year over a 25-year period from 1990 to 2014. This study finds that commercial institutions in the MENA have only a limited positive correlation with trade volume and while there is a direct positive correlation between economic integration and peace in the region, this is quite limited. These findings suggest that the conclusions made by previous studies demonstrate a direct positive correlation between commercial institutions (and economic integration more generally) and peace, may be less applicable to some regions such as MENA.


2020 ◽  
Vol 19 (1) ◽  
Author(s):  
Ludovica Ghilardi ◽  
George Okello ◽  
Linda Nyondo-Mipando ◽  
Chawanangwa Mahebere Chirambo ◽  
Fathy Malongo ◽  
...  

Abstract Background Declining malaria prevalence and pressure on external funding have increased the need for efficiency in malaria control in sub-Saharan Africa (SSA). Modelled Plasmodium falciparum parasite rate (PfPR) maps are increasingly becoming available and provide information on the epidemiological situation of countries. However, how these maps are understood or used for national malaria planning is rarely explored. In this study, the practices and perceptions of national decision-makers on the utility of malaria risk maps, showing prevalence of parasitaemia or incidence of illness, was investigated. Methods A document review of recent National Malaria Strategic Plans was combined with 64 in-depth interviews with stakeholders in Kenya, Malawi and the Democratic Republic of Congo (DRC). The document review focused on the type of epidemiological maps included and their use in prioritising and targeting interventions. Interviews (14 Kenya, 17 Malawi, 27 DRC, 6 global level) explored drivers of stakeholder perceptions of the utility, value and limitations of malaria risk maps. Results Three different types of maps were used to show malaria epidemiological strata: malaria prevalence using a PfPR modelled map (Kenya); malaria incidence using routine health system data (Malawi); and malaria prevalence using data from the most recent Demographic and Health Survey (DRC). In Kenya the map was used to target preventative interventions, including long-lasting insecticide-treated nets (LLINs) and intermittent preventive treatment in pregnancy (IPTp), whilst in Malawi and DRC the maps were used to target in-door residual spraying (IRS) and LLINs distributions in schools. Maps were also used for operational planning, supply quantification, financial justification and advocacy. Findings from the interviews suggested that decision-makers lacked trust in the modelled PfPR maps when based on only a few empirical data points (Malawi and DRC). Conclusions Maps were generally used to identify areas with high prevalence in order to implement specific interventions. Despite the availability of national level modelled PfPR maps in all three countries, they were only used in one country. Perceived utility of malaria risk maps was associated with the epidemiological structure of the country and use was driven by perceived need, understanding (quality and relevance), ownership and trust in the data used to develop the maps.


1980 ◽  
Vol 12 (1) ◽  
pp. 143-149 ◽  
Author(s):  
Dennis DiPietre ◽  
Rodney L. Walker ◽  
David R. Martella

Since the mid-1940s, interest in the interrelationships of subnational economies has been growing. Part of this interest flows from a realization of the need to manage regional growth and mitigate the effects of economically unstable components of regional economies on the welfare of the people within the region. Aggregated macroeconomic models applied at the national level commonly provide insufficient information about their components, the regional economies. This lack has led to the development of state and regional macro models which can provide specific information relevant to state or local decision makers. Such information includes the availability of regional resources necessary to support and expand regional production and the impacts of changes in demand on the welfare of local inhabitants. These models are also useful in estimating the impacts of national policy on regional economies. The development of regional input-output models is an example of the trend toward fuller understanding of regional economies. State or regional input-output models can be constructed either by survey or by estimation from the national input-output model. Time and money constraints have increased the popularity of the latter approach among regional economists.


2020 ◽  
Vol 18 (1) ◽  
Author(s):  
Njekwa Mukamba ◽  
Laura K. Beres ◽  
Chanda Mwamba ◽  
Jeanna Wallenta Law ◽  
Stephanie M. Topp ◽  
...  

Abstract Background While HIV programmes have started millions of persons on life-saving antiretroviral therapy in Africa, longitudinal health information systems are frail and, therefore, data about long-term survival is often inaccurate or unknown to HIV programmes. The ‘Better Information for Health in Zambia’ (BetterInfo) Study – a regional sampling-based survey to assess retention and mortality in HIV programmes in Zambia – found both retention and mortality to be higher than prevailing estimates from national surveillance systems. We sought to understand how Zambian health decision-makers at different health system levels would respond to these new data, with a view to informing research translation. Methods We interviewed 25 purposefully sampled health decision-makers from community, facility, district, provincial and national levels. During the interviews, we shared retention and mortality estimates from both routine programme surveillance and those generated by the study. Transcripts were analysed for inductive and deductive themes, the latter drawing on Weiss’s framework that policy-makers interpret and apply evidence as ‘warning’, ‘guidance’, ‘reconceptualisation’ or ‘mobilisation of support’. Findings All decision-makers found study findings relevant and important. Decision-makers viewed the underestimates of mortality to be a warning about the veracity and informativeness of routine data systems. Decision-makers felt guided by the findings to improve data monitoring and, acknowledging limitations of routine data, utilised episodic patient tracing to support improved data accuracy. Findings catalysed renewed motivation and mobilisation by national level decision-makers for differentiated models of HIV care to improve patient outcomes and also improved data management systems to better capture patient outcomes. Inductive analysis highlighted a programmatic application data interpretation, in which study findings can influence facility and patient-level decision-making, quality of care and routine data management. Conclusions New epidemiological data on patient outcomes were widely seen as informative and relevant and can potentially catalyse health system action such as using evaluations to supplement electronic medical record data to improve HIV programmes. Formative evidence suggests that targeting research dissemination at different levels of the health system will elicit different responses. Researchers supporting the translation of evidence to action should leverage all relevant levels of the health system to facilitate both policy and programmatic action.


Kybernetes ◽  
2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Omer Cinar ◽  
Serkan Altuntas ◽  
Mehmet Asif Alan

Purpose The purpose of this study is to determine the relationships between technology transfer, innovation and firm performance. Design/methodology/approach The relationship between technology transfer, innovation and firm performance is examined by using data obtained from 252 Turkish export firms, which are among the top 1,000 firms in terms of export volume in Turkey. To examine these relationships, a theoretical framework is empirically tested using structural equation modeling and tested via an empirical study of Turkish export companies. Findings The results of this study can benefit policymakers in government at the national level and company decision-makers at the firm level. Furthermore, an understanding of the relationship between technology transfer, innovation and firm performance may help firms to make correct technology transfer decisions and focus on the correct type of innovation to increase firm performance in practice. The findings indicate the positive effects of technology transfer on innovation and firm performance. In addition, innovation mediates the relationship between technology transfer and firm performance in Turkish export companies. This study suggests that decision-makers should transfer the right technology because well-realized technology transfers lead to the improvement of corporate innovation capacities and improvement of firm performances for export companies. Originality/value There is no study that fully examined the relationship between technology transfer, innovation and firm performance. The proposed literature-based theoretical framework in this study is novel for Turkish export companies.


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