Traditional agriculture is the main source of national food competes with imported products and mostly made by small producers. In recent decades, various policies have been implemented to support this type of farming, such as improving yields through new seed varieties. After trade opening in 1990, this was affected by import products, therefore was adopted mechanisms for protection and price stabilization. On the other hand, in this decade, public spending in infrastructure increased substantially vial. However, several studies show that the situation of small farmers in this agriculture has improved just slightly despite the fact that for example the policy of improving varieties has been successful in increasing yield improvement.
Singapore is one of the worlds most rapidly ageing nations, and the country is facing a number of health care policy issues, particularly including the care and treatment of ageing-related dementia. To help inform policymakers about dementia treatment and care, we constructed a System Dynamics model that addresses changing population characteristics, incidence and prevalence of dementia, and a population-level natural history of this pernicious condition. This article (a) describes how a discrepancy between measured census data (reference modes) and simulated population led to improved estimates of the population, (b) introduces a novel and generalizable means to simulate how the prevalence of mild, moderate, and severe dementia is likely to change over the next 20 years, and (c) provides comparisons between two means of prevalence estimation.
While there are many models of what would constitute effective health practice, the theories that people use to implement them are less well articulated. However, those charged with designing the implementation programmes for these models of health practice have internal mental models that comprise their theories of change and which guide their actions.
In this paper a novel non-smooth model for a national energy market and its extension to n-countries is proposed, showing several differences from the traditional smooth models. The study begins with the classical treatment of system dynamics theory and jumps to non linear dynamical systems theory finding mathematical results about its complexity. Such results are important in creating processes of integration energy policy between countries, as for example in the latinamerican region, because trough of bifurcations diagrams (from dynamical systems theory) is possible to know what are the all possible scenarios of the system giving robustness to the decision making.
This paper examines dynamics following introduction of nutritious food by a company well known for high-motivational and low-nutritious products. Employing a system dynamics model, we investigate how consumer dynamics affect uptake of the disruptive product. Our example is the burger chain McDonalds, which introduced salads, fruit and other healthier options in the early 2000s. Focusing on consumer choice, we analyze the process of newcomers trying McDonalds and either becoming core customers, or not. It is important to distinguish overall post-introduction commercial success, from sales of the new product per se. We examine conditions that separate commercial success (by drawing in new types of customers, whether these are the profitable ones or whether they simply accompany more burger-eaters), neutrality (in which existing customers simply change over), or failure (by alienating existing customers so that they abandon the company). We focus on the role of heterogeneity in products and consumers, and on interactions with network effects. We consider in detail the large and inertial installed base of pre-existing burger eaters, and the degree to which its dominance is hard to unseat, drawing parallels with reactions to other disruptive and 'progressive' products in industries ranging from consumer products to electric vehicles to utilities.
The advent of Internet and other communication technologies has drastically increased the volume of communication in human societies. One might hope that increased communication will lead to a higher degree of mutual understanding and resolution of conflicts. An opposing, and somewhat counter-intuitive, point of view is that the reduction in the cost of communication would make it easier for people to interact with other like-minded individuals despite geographic distance, thereby polarizing the society. In this paper, we study some of the basic dynamics underlying this problem. We develop an agent-based model to capture the dynamics of an online community where agents post stories and read and vote on others stories. We show that different combinations of parameters can lead to different macro-level behavioral modes in this model, and give anecdotal evidence from a large online community to support the predictions of the model. In particular, we identify four types of communities based on their dynamics: majority dominated, competitively polarized, converged, and diversified. We discuss the implications of each of these forms on the social welfare and the stability of the community.
The ECOWAS region (Economic Community of West African States) has big potential, but it faces major challenges in its development. To help support the decision making of regional and national leaders and bring a wide variety of stakeholders from all member states into policy debates, the ECOWAS T21 model was developed. The initial focus of the model was to test the consequences of regional integration of 1) free movement of people and commodities; 2) integrated energy, transport, and telecommunication infrastructures; and 3) creating a monetary union. When building and calibrating the model, another challenge was identified: fast population growth would make it difficult to improve the well being of the people in the region, even with successful implementation of regional integration. As a result, a family planning scenario was added. Results from the model show that a combination of regional integration and family planning policies generates the best results: smaller population, longer life expectancy, higher GDP, much higher per capita GDP, higher total government revenues, a lower poverty rate, a lower unemployment rate, more forest land, and higher per capita cereal production. However, any good policy could have its costs, such as higher oil demand and lower oil exports in this case.